Hi guys. I just got brand new UM2 and started to using it with PLA. After a few prints and overall happiness i tried to use white ABS. It is noticeable harder so first push of filament in filament pusher area behind UM2 was noticeably harder. Then i tried to print some stuff but overall prints were bad looked and not solid at some thin areas. Then i also tried a Flex PLA and again no luck (maybe just settings and tuning). And now the problem. I finally replaced the filament back to PLA and i noticed that motor that fills the filament inside was randomly cogged and make small "kkk" noise, you guys i think call this retraction if im correct (at first usage of PLA there was not any of this sounds), so now always as this occur there is a lack of filament in print at this point for another few mm? Tried almost everything and also with a different Cura versions, retraction ON/OFF, distances etc. Heating from 200 to 240, silament delivery from 50 to 200%, speed from 20 to 150mm/s etc... Also tried to tighten/loosen the strength screw for cogwheel of the motor. On this picture it is the best possible way to print everything else was worse !
Every help is appreciated...