The game always powers up in audit mode even with new batteries.

Battery holder looks fine but makes no contact

Cause: Corrosion breaks the faces off the riveted contacts in the battery holder.

Checks

• Look at each contact rivet; a missing face means no contact.

Fix

• Replace the holder; Williams A-15814 black plastic holder is a good choice, or mount the batteries remotely.

Systems

• Williams System 3
• Williams System 4
• Williams System 6 / 6A
• Williams System 7

Related tips

• Replacement battery holder for the CPU board
• Better battery holder for System 11 CPU boards
• New batteries but still losing settings: test the holder
• System 3 with no batteries boots into audit mode
• Boots straight into the adjustments menu: corroded battery holder
• Game powers up in audit mode
• Audit mode with under 3.6 V at the RAM
• Lights up but dead after storage: leaked batteries on the board

Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part One, Clay Harrell (pinrepair.com)