No, as far as SW go they work or don't work. Try cleaning the sleeve of the coils and clean and oil the pivot points.

Try cleaning the zero position switch on the bonus unit. Dirty contacts will present an increased resistance, causing weak operation of coils.

Say what?

Chris is right, sleeves/plungers can be cleaned and polished. I usually polish them up with Meguiars paste wax before reassembly. No lubrication what so ever on sleeves/plungers.

Plastic on plastic -or- nylon on nylon -or- either of those on metal do not get lubrication.
Generally speaking metal on metal moving parts should get lubrication, either a good quality grease or -a drop- of oil.

Cleaning out the old lubrication, general cleaning and re-lube should be part of a regular pinball maintenance schedule.
Me?
I prefer to do this regular maintenance on all my EM games and jukebox in the spring. Cleaning old lubrication, applying new. Remove the PF, flip upside down and carefully inspect for unusual wear, parts which worked loose etc. PF gets cleaned/waxed, cab vacuumed and blown out with air etc.

My major maintenance schedule is every 5 or 6 years. All points get a light cleaning, steppers get disassembled/inspected/cleaned. Any sign of rust gets stopped. I do everything in a regular maintenance schedule and also replace PF rubbers, polish plastic posts, touch-up etc.