I recently got and assembled the UMO+ and was able to get a few good prints out of it after some trial and error. However, I was also getting some burnt "boogers" of plastic all over my prints (I say burnt because the grey plastic was turning a brown color). At the time, I didn't mind too much because any that were left over were easy to break off the prints and they still looked good. However, a few days ago I did a print over night, and I think the print head got very clogged, I'm assuming because of running into all of those boogers as it was still printing, the result of which caused the plastic to stop moving through the print head, and the extruder to grind up the plastic filament because it wasn't able to push it through the bowden tube anymore. I've been in the process of cleaning out the print head, aluminum block, etc. (everything around the nozzle got nicely coated in melted plastic). If you have any suggestions for that, I'd be glad to hear them.
However, the biggest problem I've found is that since then, I'm not able to control the extruder motor anymore. It was working for a little while after the initial failed print, but now it just won't move the motor at all. Just as a quick troubleshoot, I tried plugging in the extruder motor to the y-motor plug on the motherboard and the extruder motor moved when I moved the "y-axis" in the Move Axis menu! However, the really bad news is that if I tried plugging in a different motor to the extruder plug (in this case, the y-motor) it wouldn't move that-motor either when I tried to move the extruder in the Move Axis menu... Does that mean that there's some problem with the electronics themselves? I've tried reflashing the firmware and that doesn't seem to have fixed it at all. If you've got any other suggestions to troubleshoot or to propose a fix, I'm more than happy to hear! Thanks.