Send your dizzy to pelican, I think they can have it fixed for you
My limited knowledge of mechanical advance is as follows:
The springs and mass of the weights work together to determine how early and how quicky the advance happens, the slots in the weights determine total advance.
Assuming the dizzy is mechanicaqlly sound as far as play/wobble, stronger springs will solve the problem as you described.
Sounds like we need to find a dizzy shoup that can spin and measure and map everything. I had a contact years ago but he specialized in "merican iron, I have no idea if he can do German stuff. I think I'll try and find his phone number if no one else has a place.
I've been thinking of sending mine out to have it checked, the other day I was setting the timing and it was wavering about 3 degrees.