The general illumination dims while the game is played.

Bally EM: GI dims during play

Cause: A fuse holder that has lost its spring tension, so the fuse sits loose. Very common on Bally.

Checks

• Wiggle each fuse; look for a loose fit or heat-discoloured clips.

Fix

• On Bally, replace the fuse holder. On most other makes the clips can be bent back to tension.
• As a stopgap, an alligator clip across the fuse and its clip holds it tight and conducts.

Unplug the game first: the power cord, fuse block and transformer primary carry 115 V line voltage.

Systems

• Electro-mechanical

Related tips

• Finding why a fuse blows: start with which circuit
• Solenoid fuse blows

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