It could be a number of things really but you may have the tensioner a bit too tight on the feeder to start. Does this happen with every spool or just the one?
However, we would be happy to help troubleshoot the material with you if you would like to reach out to us at Support@Matterhackers.com
Sorry to hear about your trouble, and sorry for the delay in response time. https://github.com/BCN3D/BCN3D-Cura-Windows/wiki/Updating-the-BCN3D-Electronics-firmwareThose are the instructions for the traditional method of updating; were you following those when "something went sideways?" What happened, specifically?
I don't see how the thickness of the belts would make any difference.Here's a test you can do for backlash. Move the X and Y axis around a bit using pronterface, so that the holding current is turned on. Then try to move it by hand. If you can easily wiggle the Y axis back and forth a little bit, then there is something wrong mechanically. Ideally, the printer should hold it firmly in place and you should not be able to move it until you apply a fairly significant force.
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