Williams Free Play
There is one switch that controls free play on a Williams game. Set the credit wheel to zero credits (shows zero credits through the backglass). On the stepper unit there will be a knotched wheel with a pin sticking out. This pin should have opened two switches only when the credit wheel is at zero credits. Adjust the top switch (or use a jumper wire) so it is permanently closed, regardless of the credit wheel position. Note there may be a second movable pin (with a slotted head). This is the maximum credits pin. Do not change the switch this pin contacts. Your Williams game is now set on free play.
Williams credit wheel: adjust the top switch (red arrow) permanently closed when
the credit unit is in the "zero" position for free play. The lower switch (blue arrow)
is the max credit switch, which opens at maximum credits not allowing the credit
unit to add any more games.