Scorched coin unit and wires with the cloth insulation burnt away.

Wiring burnt after contact cleaner was sprayed

Cause: Contact cleaner sprayed on the bottom panel ignited from switch sparks.

Checks

• Inspect all cloth-covered wire around the burnt area.
• Check the bakelite plates on nearby units for brittleness.

Fix

• Replace every burnt length of wire.
• Expect to replace bakelite plates on the burnt unit, since heat leaves them brittle.

Systems

• Electro-mechanical

Related tips

• Wire insulation shrunk back at a connector pin

Source: Repairing Electro-Mechanical (EM) Coin Operated Games to 1978, Part One, Clay Harrell (pinrepair.com)