The game will not take more than one credit, bookkeeping looks wiped, or replay levels will not set.

Only one credit, blank bookkeeping or replays will not set

Cause: The Z22 CMOS RAM is not working, often because of noise on +5 V.

Checks

• Before replacing Z22, check capacitor C2 (220 pF) on the power supply board.

Fix

• Replace a bad C2.
• Replace C24 (0.01 mfd), the RAM decoupling cap on the CPU board.
• Then replace the Z22 RAM if needed.

Systems

• Gottlieb System 1

Related tips

• Spare chips for System 1 boards
• The six Rockwell "spider" chips on the CPU board
• Which spider chips fail and why
• Swapped U4 or U5 spider still does not work
• Check the TC3 jumper plug on the CPU board
• Odd high scores usually mean a bad 5101 RAM
• Aftermarket System 1 CPU boards
• Dead CPU board: first checks

Source: Gottlieb System 1 Pinball Repair from 1977 to 1980, Clay Harrell (pinrepair.com)