Filament jamming when leaving hot end  

Filament jamming when leaving hot end

Well this is whats happening with my i3mk3.5 MMU3. I need some help

I have MMU3 up and running for about a month and for the most part it ran pretty good. There is a steep learning curve. I was able to run about 6 of the identical parts no problem same PLA filament same program. Then it went to shit. On the retraction from hotend the tip of the filament looks like a J (See Picture). It gets hung up on the entrance of the PTFE tube (from hotend to MMU3). Motors grind loud. MMU3 grinds a grove in filament feed. After this happened about 4 times in a row. I started testing. These are the things that I have done.

Cold pull. (3 times)

I have recheck MMU3 drive pulley wheel alignment. (On a side note Prusa please design spacer washer between pulleys. This would make aligning everything so much easier. You would only have to align the first one. Then everyone after that would be aligned. Doing each one by eye is asking for errors.)

I have tried to load from slot 1 to hotend than load slot 2 to hot end. Every time from either slot 1 or slot 2 the filament gets jammed on retraction at the entrance to PTFE tube (end of filament looks like a J) motors making a loud noise. Filament at MMU3 drive grinds grove in filament. The filament is very hard to get it out (lots of force required to get it out of hot end). I have tried this about 10 times and get the same results. Where should I look, what should I check?