A slingshot gives only a weak kick when the ball hits it, but fires properly if its switch blades are pushed fully together.

Slingshot barely kicks unless both contacts are pressed together

Cause: The capacitor or resistor on the trigger switch is broken (open). In one Flash case both had failed, on opposite sides.

Checks

• Inspect the 22 MFD capacitor and 100 ohm resistor on the sling switch and their solder joints.

Fix

• Replace both parts (resistor to the capacitor positive side, capacitor negative to the black wire).

Systems

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

Related tips

• R21 value on early power supplies
• Add two test LEDs to a System 7 CPU board
• Reducing hum on a type 1 sound board
• Weak pops or slings: check the trigger switch RC parts

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