UPD:
Spend many hours going through each arm, sanding, and making sure there absolutely no binding anywhere, replaced the screws around the gear with ones that have smaller cap (as suggested by @RandomDave here What a difference 1/10th of a millimetre makes (how I got retraction to work at force 3/4/500)). Got it to retract at 300. Also found a broken magnet gear:
Calibration went ok:
I tried jogging it around, seems better, less stressed. There is still a small lift up of the sled when going from left corner upwards (right side is fine).
Is there a different vacuum shroud design that won’t cause the belt twist?
I don’t think it’s the cause of the lift, but still not ideal.
I also measured the exact offsets for the belts, I think thats how it’s calculated based on what people have suggested.
I’m going to do a test cut to see where things are.