Quote Originally Posted by printbus View Post
One thing you could check before disassembly is to remove the filament from the extruder and see how easy the large gear rotates with steppers disabled. On one extruder build, I evidently hadn't tightened the second nut on the large gear enough, and with use the large gear was slowly rotating itself tighter to the extruder. By the time I noticed that, I could barely rotate the large gear by hand when I tested it.
When I checked the large gear in the manner you suggested, I found that it can move a few degrees either way without the hobbed bolt rotating. Pretty clear that I did not tighten the jam nut tightly enough in the back. I can get rid of the play by holding the head of the hobbed bolt and turning the gear. I am going to run that way for a bit and see if it will stay snug. But I am making plans to disassemble

Thanks for the insight.

Jim

EDIT - nope, running temporarily not going to work. When reversed, the gear loosens again immediately. This also explains why the problem just showed up in a print rather than only in calibration. The particular object I was printing needed a bunch of retractions. So I am guessing that the bolt became very loose during the print, resulting in an almost complete loss of extrusion.