I posted this to a very old thread last night and decided I better create a new post.
I'm having a problem with Sure Shot's bonus count: When the ball drains, you're supposed to receive 1,000 for each lit ball. But my bonus scoring is sporadic at best. I manually lit up all 15 balls and then drained it. I would get somewhere between a couple thousand and maybe 5,000. I could hear the bonus unit cycle through the three sets of five steps. But it clearly was not scoring 1,000 for each step. Several times I also heard a buzzing from underneath the playfield. I lifted up the playfield and saw the Z relay (Bonus Score Relay) was still energized.
I did what a previous pinsider described in his post: Lit up all 15 balls and then manually closed the outhole switch just briefly - enough to move the score motor 120 degrees and the spring contact in the bonus unit would move 5 positions. I did it again and it moved another 5 positions. Third time it moved another 5 positions. Then the fourth temporary closure of the switch resets the bonus unit. So the bonus unit appears to be working correctly.
But what I noticed was the Z relay energize and often would not stop. So instead of getting 1,000 X 5, it only scored 1,000 points. Sometimes it would do one quick burst, pull a second time and then continue pulling. In that case it would score 2,000 bonus. Sometimes, the coil would stop pulling and then I would close the outhole again and the same thing would happen. Sometimes the Z relay would "pulse" and I would get 2,000. Other times it would stay energized and not release and I would only score 1,000. Sometimes it would stay energized and when I temporarily closed the outhole switch again, it would stay energized through the next cycle and I wouldn't score any bonus for that cycle.
I also manually pushed in the plunger on the bonus unit and manually stepping through each contact. Every one of the 15 contacts worked - and when the Z relay functioned correctly, it would score 15,000 points (1,000 points 15 times). But often when I pushed the plunger, the Z relay would energize and stay energized. I had to manually touch the plastic armature to release it.
At first I thought the spring that releases the armature was not strong enough to pull it back into position. But I replaced the spring with another one that was slightly smaller and it didn't help. I now think that something is causing the coil to stay energized, rather than pulsing five times (for each cycle) like it is supposed to. But I'm not well versed in reading the schematic and can't figure out what is causing it to stay energized. Suggestions?