My '66 Williams Casanova beater box is getting pretty close to complete functioning.. But one issue it has is baffling me. In the backbox bagatelle feature, there are five lanes, marked 100,300,500,300,100. They all score as they should. EXCEPT the 300 point lane on the left side usually fails to advance the ball count stepper. Obviously there are two sets of contacts and one contact on that one switch isn't working. Nope. There's a single switch in each 300 lane, wired in parallel. One wire, two switches, one circuit. The right hand lane works fine. Ball hits switch, ding ding ding! 300 points, click click next ball. Ball hits Left lane switch, ding ding ding, 300 points, no click click. Same ball in play when outhouse kicker kicks. It's one wire! What am I missing here???? I've had the switch all apart, adjusted the ball rest switches, i'm stumped.