[Solved] MMU prints missing layers  

MMU prints missing layers

Hello!

I can't use the MMU3.

The problem I am seeing is that there are layers where one color will not print. Funny enough, the other colors print just fine, at least for those layers.

The problem has presented itself on primarily a couple of colors, while one color has always printed fine. Also, I never once had this problem with MMU2. The biggest problem has been using Prusament PLA. 

I have chatted a couple times with Prusa Help technicians but my problem has not been resolved. First they had me do a cleaning pull, but there was no problem in the hotend, it came out clean, but I also repeated that. They had me turn out the extruder gear tension. I turned it out 1/2 turn at a time (then I tested with a print), 2 full turns (starting with screw head flush to the left side body, without filament present). I never saw an improvement.

I have a print that I have been trying to accomplish for the last 2 weeks, and the print fails every time. The problem is in the extruder. Upstairs the MMU3 works wonderfully, no problem with loading to the extruder. I re-adjusted the filament sensor, and made it as un-sensitive as possible (so it would barely sense the filament was loaded), but it isn't sensing that the filament is not making it past the gears. 

How come the filament is not being fed to the extruder, but the filament sensor is not seeing the problem?

If anyone has an idea of what to try, I am all ears. I think the handoff to the extruder is not working correctly, and that the MMU3 needs to push the filament a bit longer as the filament starts to be engaged by the extruder gears.

Mike