I have a Monoprice Maker Ultimate (which I believe is a rebranded Wanhao Duplicator 6). Other than a loud fan it’s worked flawlessly for months. It sat idle for about a month (turned off) over the holidays and ever since I’m seeing a strange phenomenon. Prints will start fine and print the first 20 ~ 40 mm of height and then the filament will stop flowing. I’ll come back to find the printer still running but the print bed has moved down and there’s a gap between where the printing stopped and where the head is now pointlessly moving back and forth.
At that point I abort the print but then I generally can’t advance the material. If I try to remove the material it’s very difficult and takes 5 minutes of sliding it back and forth. When it eventually dislodges the end of the filament is distorted like in the attached picture.
All the settings are exactly as they were before. At first I thought the filament might have gone bad even though it had only been a month, but I opened a brand new sealed bag (it’s all 1.75 Hatchbox PLA) and the same thing happened.
I miss my printer! 
Any idea what might be going on? Thanks!!
Need details.
Temps, speeds etc.
Also retraction settings?
My guess is that it is printing a bit fast and too hot.
Mine did the same thing. I found that the extruder gear was loose. It had also moved on the shaft so it wasn’t contacting the filament properly. The gear can be pushed back on the shaft and that’s wrong. It needs to be far forward on the shaft. That probably won’t make any sense unless you find yours is loose.
Also it seems that your printer could benefit from a Cold Pull, just for a good measure…
Thanks for the tips everyone. It ended up being a partially clogged nozzle. I took the nozzle off, heated it up with my heat gun and scraped the inside out with a needle for awhile. Got it to where I could pass a thin needle most of the way through from either direction, put it back together and it’s back to printing perfectly. I’ll add that step to my occasional maintenance list!
