Update after holiday and other project.
In credit mode the pawl/rachet combination on hopper did not work, so rachet moves 2 steps and not 1 at the time meaning wrong counting. All wins were counted only half on register.
After long fiddling with pawl, springs, coilstops, coils it looked like the stroke down of the plunger in the counting coil was little too long so adjustments were not possible. I placed very thin washer on coilstop and stroke of plunger is now somewhat shorter. This seems to work for all counting except for win 20, 200 and 250.
For 1 coinplay, win 20 gives 19, win 200 gives 150, win 250 gives 200; all other 1 coins wins are ok
For multiple coins win 20: 2 coin win 40 gives 38, 3 coin win 60 gives 57, 4 coin win 80 gives 76, 5 coin win 100 gives 95 and 6 coin win 120 gives 114.
Sames is valid for win 200 and 250
Any idea what to check next?