A playfield magnet, motor or similar device works only sometimes, or not at all.

Playfield magnet or motor intermittent or dead

Cause: The under-playfield driver board (relay or FET type) has cracked solder joints from playfield vibration.

Checks

• Inspect the board's joints, especially the relay or transistor pins and the connectors.

Fix

• Reflow the cracked joints.

Systems

• Data East CPU Version 1/2
• Data East CPU Version 3
• Data East/Sega CPU Version 3b

Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part One, Clay Harrell (pinrepair.com)