Recently the ball return coil quit working (the coil that kicks the ball to the plunger lane). The coil actually kicks when I put a voltmeter to it and it reads both lugs are getting 35V to them. This was only a problem when the ball drained BUT now it shows "3 balls missing". I am a beginner and this is my first pin. I'm looking for advise/ideas on how to fix the problem. Any advise would be appreciated!