With the machine off try running a vacuum cleaner hose pulling out the exhaust. A new fan will spin up, a clogged fan will not. If you can have the fan spinning into a vacuum hose it may break up some gunk and the vacuum cleaner will take in what it can. The cleaner recommended by Support has arrived in town but I have not gotten it yet. I am hoping it will dissolve some of that and bring the fan back to newish. Alternatively an inline fan helping out is a good idea.
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what cleaner is recommended… my machine doesn’t even sound right when it’s cutting anymore either… Ill try
it doesn’t even sound right… so im sure their is something more going on! Ill see if it’ll allow me to post video here.
Like forcing itself to even work properly
Hard to tell from the audio what difference there might be in the sound, but the exhaust fan is working judging from how the smoke is being evacuated to the left, and how quickly the interior clears.
The only reasons I know of for smoke exiting the machine anywhere except the vent is the grill guarding the exhaust fan gets restricted from accumulation or a leak in the vent tube connections.
The exhaust fan pressurizes the vent tube, so the connections need to be good. Others have used aluminum vent tape to ensure a seal at the connections, but I just replaced that spring clamp that is supplied with a standard screw type clamp and I have zero smell.
When I start smelling odor, I know it’s time to clean that vent grill.
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read down for much conversation
Soon, maybe tonight, maybe tomorrow, depending on when I can get a chance to do it…I’m going to do a little writeup on something I found when I went in to clean my exhaust fan.
In my opinion, the exhaust fan needs to be cleaned periodically to lengthen the life of the fan, and it’s not an easy thing to reach.
But it can be done if you’re patient, and without the need for special cleaners. You are going to need to invest in some long specialty cotton swabs, and pipe cleaners are a handy addition as well. Keep an eye out for it. 
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I have now cleaned the Head fans on several occasions and cannot emphasize enough how much better they get. The blades look terrible all bumpy and all, but it is the bearings and places you cannot see that need to be free of resistance, and I cannot imagine how to get at those without some sort of cleaner, even on the cotton swabs.
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I’m afraid if you want to try to get into the exhaust fan to clean it to that level, it’s going to require removing the cover…and that is going to void the warranty. 
If you get one of these cable cameras, (it’s been a good 40$ investment, IMO) you’ll see that the bulk of the buildup is on the front of the blades…or I should say, the side that faces the front of the machine. The fan hub is closed on that side, so any buildup of resin is on the outside of it - probably not going to impact the inner workings much, and it hasn’t done anything in ten months that I can tell.
The blades were a different matter…they caught a lot of buildup.
If you want to, you can always spray electronics cleaner in there. Problem with that is, it removes/dissolves grease, and I thought bearings were supposed to stay lubricated.
(Don’t know much about motors…that’s the hubs department.)
I have very specifically asked for permission to Not void the warranty. Otherwise I would have sprayed it down some time ago. In the case of the head fan I already had a warranty replacement and so felt I could experiment there. Now I am hesitant to install it as spraying that one down would void the warranty.
Whatever the details the empirical facts are that it gets slowed to a stop by crud and washing down by the material known to do a good job dissolving crud allows the fan to spin up again. If it were only the blades surface it would not slow the fan to a stop, and even now the blades are all bubbly from being overheated yet cleaned up it is 80% the value as new so technically the blades are still as bad as ever but it is the resistance to spinning that has changed.
It is quite possible that the places where the crud is applying that resistance is between two moving areas and specifically not the sealed bearings.
I suspect strongly that there is a huge difference depending on what is cut. MDF and oak plywood are far dirtier than say maple and pushing through the larger gunk producers and not much tile, or maple, or acrylic would produce the effects on one and not another.
No, you misunderstood - what I meant was… removing the cover on the unit will void the warranty, but you don’t have to do that to change out the head fan. You do have to take off the cover to get to the exhaust fan at the rear of the machine on the Pro models.
And I’m glad to hear than cleaning the head fans makes them run better…I clean those when I clean the lenses, but those haven’t had a lot of buildup on my machine yet.
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I understand that. I was told that I could send the machine back for warranty work. But the getting the machine ready for shipping would be a major challenge to say nothing of setting it back up or the withdrawal of not having it.
I do not do any removing to clean the head fan but to douse it with cleaner while the vacuum cleaner pulls it through and out the other side taking some volume of cleaner with the goop dissolved in it. Then I continue running the fan for 30 min to an hour or more so there is no liquid cleaner around when I turn the machine back on.
It would be possible to do that with the main exhaust as well spraying it with a turkey baster while pulling the air through, but it would take more volume to spin up the fan than the vacuum cleaner can muster.
Once there is cleaner and goop involved parts moving past each other the goop will dissolve fastest there and we can bring the exhaust volume back up.
As yet I keep finding the oak plywood the most versatile material and the cheapest per square foot . it takes engraving well and full size of the tray is not a problem plus the oak is the strongest as well and good thick plys on each side, , so I would hate to not have it in the arsenal.
Thanks for posting. I’m glad you contacted us about this. Unfortunately, like @PrintToLaser, I’m not sure I can make a diagnosis from the video.
Even with proper filtration, small amounts of smoke and fumes can enter the air around your Glowforge, producing a detectable odor. You may also smell an odor when you open the Glowforge lid, even long after a print is complete. This is not harmful.
However, if you detect a strong, sharp smell that also causes eyes, nose, or throat irritation, or if there is visible smoke escaping while the lid is closed, shut off your Glowforge unit immediately. Smoke and fumes could be entering the room in excessive concentrations.
We’ve created a troubleshooting guide with illustrations. It sounds like you’re already doing most of these, so I recommend checking #5 and #7 specifically: https://glowforge.com/support/topic/troubleshooting/print#excessive-smoke-or-fumes-during-print
If you’re still seeing or smelling excessive smoke or fumes when using Proofgrade materials, we’re here for you. Please include the following in your reply:
- A description of where the smoke/fumes are coming from: the door, lid, or hose
- Photos of your Glowforge and your exhaust system
Thanks in advance!
It’s also surprisingly (to me) easy (to me) to block the intake fan on the right side of the machine. Say, for example, by having some bit of paper or a plastic bag nearby that gets sucked right up against the fan opening.
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Well now the fan behind the laser head is not spinning…Didn’t notice it was something to see when someone in glowforge fb group mentioned it. Today my acrylic caught fire and melted sides of my crumb tray… each time I try to cut on acrylic a huge flame goes on.
Stop cutting with it now, you’ll want to wait to hear from Support before trying to use it again.
Support will probably want to see pictures of the melted acrylic and the melted tray, so if you can post those or send it to them in an email it should speed up the resolution. Also, they’ll probably need to know the date, (9/04), time and time zone of that print. 
They’ll probably also need to know whether it was Proofgrade acrylic, and whether you were using the default settings or not.
Good luck getting it resolved. That sounds kind of scary.
its working fine now… it was the back fan of the head… im cleaning it now and seems to be fine now… but will double check
That’s the air assist. It helps things like keeping flames at bay. I’m surprised you had to clean that at all… not sure how debris would even get in there really. I wonder if cleaning it actually fixed some connection issue instead. Maybe others will chime in on that.
I’m sorry to hear about the further trouble.
Since you already emailed us about this and we’re working on it there, so I’m going to close this topic.