Dick Merchant wrote, "the driven wheel wants to drift as close to the
driving wheel's axle as it can go and stay there."

I haven't personally encountered the problem.  But, for certain clients
who have a tendency to change the tempo a lot, I place an appropriately
sized and tensioned coil spring fragment, approximately 1/2 to 1 inch
long, over the shaft between the tempo wheel and drive shaft socket.
Lubricate it with graphite grease and it will counter the force of the
tempo adjust screw mechanism.  This is a 'minor' improvement and isn't
too far from what a factory solution might have been.

Good luck,
Stephen Kent Goodman
Fresno/Clovis/Tarpey Village, California

 [ Inspect the axle alignment.  The wheel on the driven shaft shouldn't
 [ wander if the driven shaft axis intersects the axis of the shaft with
 [ the flat (driving) disc.  -- Robbie