Flippers are weak, cut out, or work intermittently.

Flippers weak or intermittent from the solenoid driver board

Cause: Cracked solder at the .156" header pins of SDB J1 (top left, the flipper ground returns to the relay), burned traces between J1 and the flipper relay, or cold joints on the relay.

Checks

• Inspect the back of the SDB around J1 and the flipper relay.

Fix

• Reflow J1 and the relay pins and repair any burned traces with wire.

Systems

• Bally MPU AS-2518-17
• Bally MPU AS-2518-35

Related tips

• Flipper weak, dead, or machine-gunning
• Flippers dead though fuses and EOS switches are good
• Flippers stop working after a few minutes of play
• Test solenoid driver transistors with the game off
• AS-2518-16 and AS-2518-22 solenoid driver boards interchange
• Solenoid driver board J3 pin functions
• No coils work at all
• Check the wire from a coil back to the solenoid driver board

Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part Three, Clay Harrell (pinrepair.com)