my friend has exact problem on his game after only 80 or so plays ball search at power on or ends ball during play flippers die, I open it up trough switches register so do optos but after looking real close 2 of the trough switches are a hair lower than the very last one. I took off the front bracket holding the switches in place and use switch adjuster bend just a little higher the two that are low and put bracket on 20 games later problem gone. This was happening on every game once it started, I am guessing when shaker motor goes off it is enough to make balls come off switch enough in trough confusing game thus ending ball in play so far so good try that.