Hi,
Now that I am retired I am attempting to get my Chicago Coin Top Ten pinball in correct working order. One current problem is that occasionally the ball index relay stays energized after the ball drains.
The sequence of events should be:
1) The ball is shot up the lane.
2) The ball passes over the lane switch and the ball index relay is energized.
3) The game is played and scoring is made.
4) When the ball drains the score motor begins cycling.
5) The bonus relay is energized and bonus points are applied
6) The out-hole relay is energized,the ball is ejected into the shooter lane and the ball index relay is de-energized.
7) Next player (or next ball in single player game) is then played.

Usually in a two player game the ball index relay fails to de-energize 4-6 times. This does not appear to affect scoring although occasionally a player's turn is skipped. The ball index problem is random. It does not matter what scores are up or what number ball is being played.
I have cleaned all the score reels, contacts on the bonus relay, out-hole relay and ball index relay.
The C3 contact on the score motor does open as it cycles. As far as I can tell that should interrupt the power to the ball index relay but evidently it is not doing this every time.

I have included the schematic. I admit I do have trouble following some of it.
I would appreciate anyone's input into where I should check next.
Thanks in advance,
Bruce

Chicago_Coin_1975_Top_Ten_Schematic_Diagram_Continuous.pdf

Thank you for the info.
Those are the areas that I have been concentrating on. I am 99% sure the C3 motor contact is operating correctly. The outhole contacts....not so positive. There are 5 sets of contacts: 2-make, 1-break and 2 sets of M/B. Whoever had the game before me really bent the heck out of a few of those contacts. To make matters worse the outhole relay is 3rd in from the back of the machine. Somewhat difficult to observe and work on.
I'll go back and clean those contacts once more and attempt adjusting them. Do you have any recommendation on what the gaps should be? Right now they vary from .007" to .015 or greater.
Thanks again,
Bruce

Thanks....I'll give that a try!

I tried Seamlesswall's solution first with putting paper between the coil and armature. I played 10 games without any problem. On the 11th game the ball index relay started acting up again.
Next I followed HowardR's suggestion and adjusted the Outhole relay contacts. After some trial and error I believe I finally achieved the correct gaps. I have now played 26 games without any problem.
I think the score motor occasionally cycles once too often but it hasn't affected game play. I'll have to do a little more tweaking of the contacts and hope that remedies the solution.
Big thanks to both of you for your suggestions!