I’ve been able to calibrate my Maslow for several months (at high force) but it wasn’t usable. I was asked to do a cut for a friend and took a very cautious approach to a simple cut, with multiple test runs (router bit removed). What I found was that the Maslow4.1 is more susceptible to spool jamming the further you go from the centre. The most difficult thing (on my 10’x8’ horizontal setup) seems to be moving in the x direction towards a corner of the work area. In the corners one belt is pulling and trying to overcome the force of 2 acting against it, whereas in the middle it is 1 on 1. This was where it started juddering (not good) and stick-slipping (very bad, wavy cuts), ultimately resulting in a position error. Note that in my case, although it looked like the left was stick-slipping, I think the culprit was another (TR, BR) belt with some residual friction.
Strangely, the (very useful) trace perimeter function didn’t identify the issue; it goes anticlockwise and my biggest problem was moving left towards BL. Moving right in the same place was smooth.
So my suggestion is that after you have sanded and got a retract and calibrate working at force <800, run further motion tests in both directions along the perimeter of the intended workspace.
Perimeter trace is really useful to make sure the job is aligned to the work piece. Would it be possible to add a direction function so that the Maslow motion can be checked in both directions at the edge prior to a cut?