Repetitive, weird shifting of layers  

Repetitive, weird shifting of layers

Hello, I have a problem I can't deal with, no matter how many solutions I tried.

So, I have assembled my MINI some time ago. First layer calibration was perfect. My first print, Benchy, was going pretty well, until the filament snapped in the middle of the printing. After some troubleshooting and writing to supportit turned out, that I tightened one screw, next to the PET tube, too much, so all I had to do is loosen it. I dissasembled everything in order to be able to tighten it and reassembled it carefuly. 

And that's when the real troubles started. Beacuse from this moment onward, my every print experience layer shifting, but in a weird, repetitive way. This is how my Benchy looks like now.

When I try to print simple tokens, from one side it looks like layers are shifting, but the opposite side of the print i usally ok, so it doesn't really look like everything shifted.

The arrow in a picture below is to show which direction token was facing while printing (the arrow points at the front of the printer).

I've tried to tweak it many different ways. I've tried different solutions from forums, mechanical and software ones, I tried to write to the support and used their ideas, I've tried to dissasemble it again to the point of the PET tube tightening and be very careful with reassembling. I used a spirit level and eveything looked ok. Nothing worked, I expeirence same, repetitive shifts. . First layer callibrations are perfect. I've tried printing in different PLA filaments.

At the end, I tried to tighten belts more and after that print belt meter. For this I've used PTEG for the first time. I don't know if it is easily visible in the pictures below, but it looked like first layers were shifting a lot in a chaotic way, then layers just moved to one side, all shifted the same way and then print came back to initial postion and everything looks good. BTW, the belt meter said belts are close to max tension.

l really have no idea what to try next, I've tried more prints and they all look like Benchy and that token. I would appreciate every tip!