The bonus unit on this machine was not correctly stepping up and down. I serviced it as per the excellent Clay guides and replaced some worn parts (step up plunger and coil stop, reset pawl). The unit now steps perfectly, both in game and when operated by hand.

Problem is, the bonus is incremented one more step after it reaches 15,000. What's wrong here? Any part(s) missing? I looked at this issue for quite some time, searched the Internet for pictures/videos of similar units, tried adjusting the bakelite plate one rivet. Must be something obvious that I simply cannot see with my limited EM experience.

Attached pictures show the unit at the 15K position.

Is the limit on this stepper enforced solely by the missing tooth? If you look at one of the pictures, a pin in the "8 o'clock" ratchet hole (protruding through) would limit the unit to travel too far. So that might be missing. The credit unit on this machine has one of these installed.

Previous owner played the machine at home and probably had little experience with pinball machines. The bonus unit never worked as it should. The machine is located in The Netherlands. I can solder, have little experience with EMs, but learning every day. Hopefully someone can provide some insight or photos of a working Bally bonus unit of the same era. Thanks in advance.

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The lit playfield insert corresponds with the active rivet in every step. Nothing weird there.

When the bonus steps one step beyond 15K, the bonus lights turn off (since there is no wire attached to the next rivet on the bonus unit). As expected, bonus adds 16K to your score in that case

Thanks for your help, Mark. Good tip on the small screw! I haven't looked at that yet or taken it apart. Will do that later today.

And yes, photos of a working Night Rider bonus unit are very much appreciated.

Thanks @swillie, these pictures clarify a lot!

Turning the wiper blades is not going to work, if I see correctly. From the zero position, it takes 16 steps on my ratchet to reach the limit position, instead of the 15 as on yours. The ratchet must have been replaced by the wrong one on my machine at some point in time.

Guess I have to cut out the tooth at the 16th position. Or live with the fact that "this one goes up to eleven"

Will let you know when this is fixed.

Today I cut out the last tooth on the bonus ratchet. Unit is working perfectly now. Steps up and down correctly and most of all, its limit is now 15K! Thanks for the help, guys.

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