So I think the problem was clogging. I tried to print pla and it run about 1 hour until it came out on side of the hotend.
During the cleaning I also found some pices of abs.

So lessoned: Check the Hotend after such funny behavior.

By the way is the makerfarm exturder the same for 1.75 and 3.00mm? If yes doesnt it make sense to use a guiding tube for 1.75?

BR
PGX3S