X-axis shifting and strange worms  

X-axis shifting and strange worms

Dear community.

I am trying to print a cover for a box upwards and   I experience problems I never had before. As you can see on the pictures there a some layer-shifts and some "worms" of filament are coming out on the left side. I tried to print severeal times. The layer-shifts are at different heights at every print but the "worms" are always on the left side but only in the front. The shifting is on the X-axis only, not on the Y-axis. I have already tried the following things:

- Printing with SD-Card
- Printing with Octoprint (Octopi)
- Bed cleaning
- Tighten all screws
- Lubricate rods
- Check tightness of belts
- Check cables
- Factory reset
- Complete calibration

Nothing seems to help... I also checked the STL and the GCODE twice but there is no error to see. The oly thing I can say ist, that 12 Y-axis crashes have been detected but nothing on the X-axis.

I'd really appreciate if soeone could give me some advice. And sorry for my bad English.

Thank you in advance!
Bernd

Slicer:
Prusa Slicer 2.3.1
Standard settings for PLA, 15% infill, no rafts or supports

Prusa I3 MK3s
Firmware: 3.10.0-4481
Belt status: X: 265 Y: 267

Fillament:
Geeetech PLA