Some switches, or a whole row or column, show closed all the time or never register.
Switches stuck on: board or playfield?
Cause: Either a playfield short or a driver board fault, including cracked header pin joints on 2J2/2J3.
Checks
- In switch test, unplug 2J2 and 2J3. If the stuck switches clear, the problem is on the playfield.
Fix
- Playfield: look for shorts (below). Board: resolder the 2J2/2J3 header pins, then check the chips.
Systems
Related tips
- Switch column or row fault on the driver board
- System 6: game stuck in tilt with switch 1 closed: cracked pins in the 2J2 plug
- Board or playfield? The switch test jumper method
- Leon test: switch column drives (2J2)
- Leon test: switch row inputs (2J3)
- A ball resting on one switch stops others in its column
- Switch matrix column test at 2J2 with Leon's code
- Switch matrix row test at 2J3 with Leon's code
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)