Targets stay down after the reset coil fires, or fall back down.

Drop targets will not reset or stay up

Cause: A gummed-up mechanism, targets worn so they sit at an angle and bind, or a broken, missing or unhooked spring (especially the return spring at the end of the bank).

Checks

• Look at each target guide for dirt and the targets for wear.
• Check every spring is present and hooked.

Fix

• Clean the bank.
• Replace worn targets and missing springs.

Systems

• Williams System 3
• Williams System 4
• Williams System 6 / 6A
• Williams System 7
• Williams System 9
• Williams System 11
• Williams System 11A
• Williams System 11B
• Williams System 11C
• WPC Alpha-Numeric
• WPC Dot Matrix
• WPC Fliptronics
• WPC DCS
• WPC-Security (WPC-S)
• WPC-95
• Bally MPU AS-2518-17
• Bally MPU AS-2518-35
• Stern MPU-100
• Stern MPU-200
• Bally 6803
• Gottlieb System 1
• Gottlieb System 80
• Gottlieb System 80A
• Gottlieb System 80B
• Gottlieb System 3
• Data East CPU Version 1/2
• Data East CPU Version 3
• Data East/Sega CPU Version 3b
• Capcom
• Electro-mechanical

Related tips

• One drop target drops by itself right after the bank resets: fit longer return springs
• Setting drop target reset coils to prevent metal fatigue
• Drop targets stop scoring or the bank will not reset
• Drop targets don't all reset fully: rebuild the reset and face the worn reset bar
• Drop target falls by itself when flippers or pops fire: wax on its ledge and weak spring
• Drop targets do not fall
• Drop targets only rise part way in solenoid test: test mode uses a shorter pulse

Source: Pinball Machine Care & Maintenance, Bernard B. Kamoroff (Bell Springs Pinball Alley)