I have an issue where my machine sometimes will launch two balls into the trough at the beginning of a turn. The issue is intermittent and occurs most often when one ball is locked in the left diversion ramp (whirlwind). I see there are three switches under the apron and a fourth in the trough. Any idea which combination tells the CPU that there is "no ball" in the trough causing the second to be kicked? Each of the four switches mentioned move freely and appear to 'click' at the point they should be triggered.