The tilt never registers, and pressing the tilt switch fires the right pop bumper instead (a slingshot fuse also blew).

Tilt doesn't work and closing it fires a pop bumper: dirty slam tilt switch

Cause: The slam tilt switch was contaminated and its blades were almost touching, upsetting the switch inputs.

Checks

• In switch test, close each tilt and slam switch and check that only its own number shows.
• Inspect the slam tilt switch for dirt, damage and blade gap.

Fix

• Clean the slam tilt switch and set its gap.

Systems

• Bally MPU AS-2518-35

Games

• Supersonic

Related tips

• Flipping scores 10 points: a rebound switch squeezed closed by new rubber
• Right outlane adds players or starts a new game: start button shares a matrix row
• Pop bumper or slingshot fires by itself; random tilts
• Closing one switch kills the whole column: slam tilt switch touching the coin door
• One switch or a string of switches never registers
• Switch reads stuck closed, or a pop bumper chatters
• Switches register with the wrong numbers
• Hitting switches in one matrix row tilts the game: bad capacitor on the tilt bob

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