That being said, I think the shaft pin slipping is unrelated. Causes for that:

- temperature set too low
- debris plugging nozzle
- geometric misalignment resulting in binding
- assembly tolerances in the coupling

Most likely, it is the last one. The shaft pub design worked well on my workbench, but variations in shaft, socket, and pin sizing plus how many layers of tape were used made this an unreliable approach when applied to 1000+ users. More here:

http://www.soliforum.com/topic/5966/no- … nswashers/

I finally got the new Filastruder and Filawinder working together great.
After about five hours of nice 1.75 mm filament I heard sort of a
bang sound. The pin sheared and it stopped extruding. Just the
motor shaft was turning inside the coupling. I took it all apart and
discovered the entire roller bearing and washer races were covered
with rust. The rollers appeared to be scored up also. Shouldn't
it be lubricated? I rechecked the assembly instructions and
did not see mention of lubricating the thrust bearing. I have
a very dry basement. Maybe the moisture came from the plywood
support and rusted the unlubricated bearing. I guess there was enough
friction from the rusted bearing to shear the pin on the motor shaft.