I have exactly that issue and have figured out that the goop and gum from evaporated wood has gotten into everything, from the fans in the laser head to the exhaust. I have requested help from support to use a cleaner that will dissolve the goop, and told that to preserve my warranty I need to coordinate with them in using the cleaner they recommend. The cleaner has issues that they recommend that it be used outside, but that is not a possibility for me, just as packing the machine up and sending it back to Seattle is a last result that will be very difficult.
It would have been a very good thing if the exhaust fan (and many other parts?) had been designed like the Laser head to just pop in place with a plug-in control cable but that has not been the case, and is harder to change than the software. We can clean off much of the machine as that goop builds up but the exhaust fan is not on that list, and even when the chatter stops and the fan spins up a lot more, but that goop slows the fan a lot even when there is no chatter. Causing the machine to leak smoke into the room whereI have this eating up any stray smoke
I have ordered the cleaner they recommend but it has not arrived as yet.