Can anyone give me any ideas why my Glowforge Pro has problems with intermittently “stair stepping” my designs, most of the time right about the middle of it. I make all my own designs in illustrator. They’re vectors saved as svg files and sometimes engrave just fine, sometimes do this. (I’m hoping to include photos). If you look closely at my photos you can see where it looks like the two halves are disconnected and have shifted slightly. 
This makes me really sad as I am all about symmetry and want my prints to be perfect. Any help or suggestions you can make would be awesome. I have cleaned and cleaned and cleaned and that doesn’t seem to be the issue. At this point I’m out of ideas.
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Stepper motor is losing steps. These types of motors move in calibrated steps, they don’t turn continuously, so the controller knows how far the laser moves for each step. But the system is “open loop”, there’s no feedback to confirm the motor stepped. Motors can be overloaded or have physical defects that cause them to not successfully complete the move when commanded. Since the controller doesn’t know it happened, everything that’s printed after the error is offset by the size of the error.
I’d check your machine to make sure the belts are tight. I’d verify that none of the belts are missing any teeth (they’re cogged belts). I’d gently move the print head carriage back and forth and left and right, especially in the area where you see your errors happening, to see if there’s any “rough spot” or binding in that region. Look under the side panels to make sure there are no wire harnesses that the moving printer carriage could be bumping in to.
More than likely, there’s some mechanical issue that’s causing the problem.
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Well that sounds like a complicated problem to try and troubleshoot myself. I’ll give those things a look . . . this is my replacement machine, so this is quite frustrating. 
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I’m so sorry to see that this is happening to your beautiful designs! A @randy.cohen already pointed out, this is likely to be a mechanical issue, and there are a few steps we can take to get to the bottom of it.
In order to better gauge the error, I’d like to have you try a test print for me. If you have any Proofgrade Draftboard material to use, it will be helpful to run the test using that so we can be sure as many factors are controlled as possible.
- Turn off your Glowforge
- Turn your Glowforge back on
- Place the piece of Draftboard we’ve provided for troubleshooting in the center of the bed
- Print the Gift of Good Measure using the default settings in about the same position in the bed where the trouble is occurring.
- Take a photo of the resulting print
- Post the photo along with the date and time of the print
If the Gift of Good Measure doesn’t print perfectly, could you also do the following?
- Wait until your Glowforge has been idle for at least a minute
- Open the lid
- Very gently, push the printer head to the right with one hand and see if you are able to move it
- Repeat the previous step, this time pushing the printer head to the left
- Let me know if you feel any difference in the resistance along the way
It’s been awhile since we’ve seen some activity on this thread.
Would you let us know if you’re still experiencing trouble @birdsneststudios ?
We haven’t heard from you, so I’m going to close this post. Should any additional questions arise, start a new post, or email us at support@glowforge.com!