Williams/Bally games using the opto ball trough (introduced in 1993) have a
tendency to develop 'divots' in the bottom of the trough that eventually
cause the balls to hang up and not feed properly. The best cure I've found
for this is to use first smooth out the worn spots with a Dremel tool &
grinder attachment. When the bottom V-groove is smooth, line the bottom of
the trough with Mylar. You need to do this carefully: kinks or high spots
will cause further problems. Don't cover the V-Groove; instead, cut 2 Mylar
strips, and carefully line up the edges of the Mylar with the edges of the
V-groove. A paper cutter works great to get the long, straight edges you
need on the Mylar strips. I've done this on 3 different games, and had no
further feed problems. As a bonus, you get less metallic 'crud' tracked
back up onto the playfield.
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