did you ever figure this out. I have almost the same problem with my left unit.
although mine doesn't seem random, it seems to happen at the same time.
I run a "load filament" and put in the filament, it starts to extrude and then slows and finally stops.. it will start up again if i push down on it, but then after 30 seconds-minute it will slow again and finally stop.
i have taken apart the unit and cleaned the gears (this unit is only a few weeks old and has probably less than 20 hours on it)
i saw a video on a maker bot, where someone fixed that type of issue by tightening up the plunger? but since our's is a different setup, i didn't know what i could try to adjust/tighten.
anyone have any thoughts?