Cleaning and aligning an EM stepper unit

Steps

• Operate the step-up and (if fitted) reset solenoids by hand; if a solenoid will not move at all, check it for a burned coil.
• Clean the mechanism with alcohol on a tissue or swab without dismantling it; do not spray contact cleaner or WD-40.
• Clean the wiper and stationary contacts with alcohol and crocus cloth or fine sandpaper until they shine, without bending the wiper fingers.
• Step the unit by hand and check each wiper contact lands squarely on its stationary contact.
• If they sit off-centre, slightly loosen the cover plate screws, rotate the wiper into line and retighten.
• Optionally wipe a very thin film of pinball lubricant on the stationary contacts; use nothing else.

Systems

• Electro-mechanical

Related tips

• What stepper units do in an EM
• Kinds of stepper unit
• Faults that point to a stepper unit
• Stepper cleaning, part 4: refit and test
• Player unit sticks: clean off old lubricant, don't add more
• Stepper cleaning, part 1: mark, check and remove the wipers
• Stepper cleaning, part 2: free a seized shaft
• Stepper cleaning, part 3: rivets, wipers and lube

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