You want to be careful with that whole replay button thing because on King of Diamonds the whole circuit runs at 120v:
King of Diamonds Replay button (resized).jpg
Since the coin chute starts a game we can eliminate some switches. With the power off, and preferably with the game unplugged, see if you can find an issue with the path in red. It's likely that one of those switches isn't closing although it could be a bad solder joint, or jones plug, etc.
/Mark