If the solenoids on your Bally pinball machine are weak or sluggish, perform
this simple test. Measure the voltage at the solenoid driver/voltage
regulator module U2 pin 24 to ground (pin 12)--You are looking for 5VDC. If
this voltage is low, measure TP1 to ground. If the voltage is OK at this
point solder a jumper from TP3 to TP1. The outboard jumper on J3 pins 13 to
25 is prone to failure.