All solenoids die or just the flippers?

Since the flippers die and its going to the next ball it in fact sounds like it thinks balls have drained and actually isn't resetting. When a ball drains it is a common setting for the flippers not work to save wear on the flippers in a route location situation. Does it count your bonus when the flippers die? If so I suspect you have something flakey with the ball trough opto boards. If you have a set you can pull from another game, yours or a friend's, swap them in. You can always pull the board with the infra red leds and look at them with the game on through a digital camera. All of them should be lit. However the receiver board you will have to use your multimeter to test it. I bet its the opto boards. You can always try reflowing solder on the connections on the opto boards. I've fixed a few this way.