The game takes credits and starts, sounds, lamps and test modes work, but no playfield switch scores, the ball isn't kicked out and pops and flippers don't respond. Swapping driver and CPU boards makes no difference.

Game starts but no switches score and the ball isn't served: corroded A1-J6

Cause: The A1-J6 switch matrix connector on the CPU board sits just below the battery; its pins had corroded and flattened so the switch matrix had no contact.

Checks

• Inspect the A1-J6 header pins and the mating connector for green corrosion or flattened contacts.
• Look at the board under the battery for corroded traces as well.

Fix

• Replace the corroded connector housing and pins (and the header pins if needed), and move or remove the on-board battery.

Systems

• Gottlieb System 80B

Games

• Bone Busters Inc.

Related tips

• Lane change from the flipper button does nothing: bad 1N270 diode
• Flippers go dead in the middle of a ball: a switch closing on vibration
• Per-game switch and lamp assignment charts

Source: Pinball Repair help group!! (Facebook group)