Re: Plug of Death :(
Some more data on this:
After about 2500 hours on my most-used Filastruder (v1.3 with v1.5 gear motor - the one I tore down when extrusion slowed at ~1300 hours), extrusion stopped again - a few mm/min.
I pulled out the melt filter nozzle, and it was clogged nearly completely. This is not unexpected, I was running some trash MG94 that had cardboard and other bits mixed in. I cleaned the nozzle and reinstalled, but no dice - same problem.
I was looking over the machine, and noticed there was basically no load on the thrust bearing. This told me that there was a plug of plastic stuck to the auger that wasn't grabbing the walls of the barrel. I stuck a flathead screwdriver in behind the thrust bearing and slid the auger forward as far as it would go (towards the nozzle) with the motor running. After about 30 seconds, the plastic seemed to grab and the motor load increased, as well as the auger slid back compressing the thrust bearing again. After this, output became the normal ~15 inches/min again.
I think in this case the clogged screen stalled the output, and the plastic stopped gripping the inner surface of the barrel. After that nothing helped short of sliding the auger forward. Interesting indeed, if it happens again I'll be sure to post more here.