Cleaning and rebuilding System 3-6 drop targets

Steps

• Remove the small circuit board behind each target (two screws each).
• Clean the contact points of the horseshoe-shaped brass wiper on the back of each target, and the board it rubs on.
• Apply a very small amount of clear Teflon grease to the contact area (Williams recommended lubrication in a June 1980 service bulletin); this protects the plating.
• Check the wiper points are intact: a missing point leaves a sharp edge that scrapes the copper off the board.
• Set the wiper tension: enough for reliable contact, not so much that the target drags.
• Do not over-tighten the wiper screws.

Systems

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

Related tips

• System 3-6 drop targets use two switches per target
• Drop targets do not fall
• Drop targets stop scoring or the bank will not reset
• Drop target does not fall when hit

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