These jumper mods are pulled from the old pinball repair site that was taken down years ago, Hope they help.
WPC and WPC-S Driver Board Jumpers:
For reference, the driver board is positioned with the solder side showing, and connector J104 at the "top". All jumpers added to the solder side of the driver board.
BR2 to C5: two jumpers. Jumper the positive lead of bridge BR2 to the positive lead of C5. Repeat for the negative leads also.
BR1: ONE jumper. Jumper the AC lead of BR1 (just below the positive lead) to connector J101 pin 7.
C6/C7: jumper the two positive leads of capacitors C6 and C7 together (this also jumpers also helps BR1).
C6: Add another jumper from the positive lead of C6 to TP8 (Test Point 8, 18 volt DC). Note this jumper is not shown in the picture below.
BR3: three jumpers. Jumper the lower AC lead of BR3 (just below the positive lead) to connector J104 pin 1. Jumper the other upper AC lead (to the left of the positive lead) to connector J104 pin 2. Jumper the positive lead of BR3 to the large solenoid fuse trace about 2" below the bridge (see picture below).
BR4: three jumpers: Jumper the negative lead of BR4 to the negative lead of C11. Jumper the AC lead of BR4 (just above the negative lead) to connector J102 pin 1. Jumper the other lower AC lead of BR4 (just below the positive lead) to connector J104 pin 4.
BR5 to C30: two jumpers: Jumper the positive lead of BR5 to the positive lead of C30. Repeat for the negative leads also.
All the above jumpers have been installed. The most important jumper
is the one from BR2 to C5 (the gray wires). Note the "+" (offset leg)
of the bridge goes to the "+" lead of the associated capacitor. The
"-" lead of the bridge is diagonal to the offset "+" lead. Shown is a
WPC and WPC-S style driver board.