UMS3 Feeder motor stopping suddenly with loud noise when changing filament (video attached)

[mikebuss 1]

I've been printing with PLA and PVA, and one day the PVA stopped feeding correctly. I tried a bunch of things, like hot/cold pulls and drying the filament, but nothing worked. I replaced the BB print core and it started printing correctly, but the print would periodically say "out of PVA filament", requiring me to click Continue. After clicking Continue, it would usually print PVA correctly, but after a few times (over the course of an hour) it stopped.

 

So, I tried unloading the PVA and re-loading it, which has helped before. When the printer tried unloading the PVA, I noticed the motor would suddenly stop with a horrible sound. Here is a video of this happening: 

 

 

Can someone tell me what's going on here with the motor? How do I fix this? What could have caused it?

 

Thank you for any help you can provide.

 

[kwakefield 1]

I am curious to know why that happens as well. I just went through having to change the filament 3 times to get it to run and load correctly. With 35 minutes left on a 10 hour print, the printer thought there was a filament feed issue. So I did a ‘change’ process and heard the clunk at the end of the loading. From experience I know it means the feeder has chewed up the filament at the very end of the load. I finally got a good load, by unlatching the feeder handle, manually removing the filament, clipping off all the material that was forward of the brutal chew marks, and re-inserting the filament all the way to the print core. Would be great to know why it happens so I can fix it quicker and not waste 1m+ of filament.