Please help. I have a UM3+ and it has worked great for the past 2 years. Suddenly the PVA in printcore 2 is not extruding. Stopped working mid-print. I have 1) cleaned AND changed the print head 2) cleaned the feeder gears - even took the whole feeder assembly apart, cleaned it out and put it back together and 3) blew out the bowden tube with air. I am at my wit's end. I have searched all over the web and there are no possible solutions or even suggestions on how to re-assemble the feeder. I have a math camp starting next week and desperately need this to work.