I appreciate you providing all of this great information, and taking some good initiatives provided by the community. Thanks everyone!
I’ve reviewed the images of the bottom of your laser arm, and while the belt does appear to have some debris and may be dirty, I do not think that this trouble was caused by a pulley slip.
I did review this particular print, and you may have found the cause of the solution in one of your additional posts. During this print, the head did not properly home, and this caused the “jump” during print you mentioned. Then, once your Glowforge is restarted, it correctly homes in the right position.
The next steps we would normally provide would be reviewing the speed, and seeing if it happens at a lower speed. This looks to also performed correctly, and you did not run into the same results or behavior.
Thank you for letting us know about this. If the snag ever happens again, in a similar manner or print type, please let us know. We’d be happy to dive in and see what could be occurring.
I’ll close this thread for now, but please don’t hesitate to open another thread or email us directly if you run into any trouble.