Mate... sometimes you have to walk away from a game for a few days to clear your head. Its very easy to tell yourself its one thing and even though youve checked this, the fault persists.. this is when you need to take a step back and more often than not the solution comes to you once your brain has had a breather.

Bonus count unit.. the  stepper in the headbox yes?

At start up, the whole game goes into reset mode... every switch on this reset has to be aligned for it to actually reset... stop and then give a game.

If all scores are resetting etc and its the bonus count unit that continues to turn then chances are that it has not found its ZERO point and so it turns and turns until it finds it.
 Did you pull this apart to clean?
Are you 100% sure you have it in the correct position when it was put back together again.
Is the tension correct so wipers make good contact?

There is also an adjustment on these for the spider wipers.. you can loosen the screws slightly and turn the rivetted plate 10mm either way... make sure the spider wiper is dead on a single contact and not inbetween 2.. its easily done.. also make sure that all leaf switches on this unit make and break properly using a DMM.. sight isnt enough.

The fuse on the step down... what size is the stepdown? Sounds like its too small or just about up to par... should always have approx 1/3rd extra power for anything like this.
 Whats happening is that the score motor is turning and coils are firing all the time its continually running... this draws quite a bit of current which puts stress on the stepdown warming it up and so it overrides and shuts itself off.
2A is more than enough for an EM stepdown so long as the game is operational...... after all not everything is working at once. If everything were to fire/turn etc at the same time then it pulls a current spike and its too much power for the step down.
Same principal is in your house.. you can run multi socket power boards from all wall sockets, but if you have everything plugged in and running then you will trip your power supply... all these things assume that you wont use everything at once.

This is a different fault to before with the bright lamps.. did this get sorted??
Also.. these issues only appeared after you pulled the game apart to repaint yes?


...just trying to eliminate/ narrow down things for you... every fresh mind helps...