Hey Erik,
the Mitz Pellicciotta method, which is a method that works the better the larger the bit diameter is, because it looks at the direction of the patterns such a bit makes when it is not perpendicular to wasteboard surface, works only as third step after you ensured your machine is
Only then I would proceed with
IMPORTANT NOTE: Surfacing the wasteboard does help nothing if the machine is not accurately rectangular (“squared”) and coplanar (not twisted)! Not at all! All your workpieces including the wasteboard will remain a parallelogram and be twisted if you don’t ensured steps 1 and 2 accurately.