the coil yanks the armature plate a lot harder/faster than you can, so if pieces are worn you may have your problem.

the one thing you can do something about is the position of the brass finger that prevents the shaft from turning backwards when the pawl is pulled back (pawl = the plastic pusher you are having trouble with).

make sure the finger has good tension against the ratchet and is positioned to hold the ratchet so it can't spin the wrong way. Loosen the screws to slide the finger to position desired.

look for other adjustments to the armature plate position ... the goal is the pawl retracts enough to reliably grab the next ratchet tooth, but not further.

if your problem happens often enough, mark one of the big alternator teeth with a sharpie and watch as you hit whatever playfield thing makes the unit step. You want to see if the shaft turns backwards or the pawl is slipping off the edge of a worn ratchet tooth.

part numbers are for a 10 step unit are:
3A-7366 - pawl
A-7595 - shaft with alternator

12 step unit:
3A-7369 - pawl
A-7567 - shaft with alternator

I don't remember if the coil screw has a brass washer on it, but if it does make sure it's between the coil and the frame (not under the head of the screw). If it needs a washer and it's not where it should be, that'll make the armature plate pull the pawl back further.

what game is it on?

mark's suggestion of a spacer washer between the coil and frame would be more reliable than the tape.

the pacific pinball museum has a prospector in the warehouse ... no paperwork tho. I can pull it out monday and take pics of the unit in that game for comparison.

typically a brass washer goes between the coil and the frame. It's there to mess with the magnetic field and help prevent magnetizing the frame.

however, I can count on one elbow the number of segasa games I've worked on in the past year, so don't know how they mounted coils. You can look at other relays in the game to compare.

if you use a steel/aluminum washer, put the brass washer next to the coil.

below are pics of the museum game.

I can't force the pawl down like yours is doing, so hopefully the pics help you find the issue.

propector_pawl (resized).jpg

prospector_coil (resized).jpg

prospector_armature_gap (resized).jpg

prospector_pawl_travel (resized).jpg

prospector_coil_screw (resized).jpg