I'm having a problem with my WCS kicking out additional balls into the shooter lane during play, eventually stacking up several of them. There doesn't seem to be any rhyme or reason as to when they start kicking out. You can play for awhile and then you can feel the coil trying to unjam the balls and then it is eventually ejected into the shooter lane. My first course of action was to test the optos in the trough. I tried that and they all checked out okay. I also tested each opto on the receiver board with a flashlight and did switch tests on all of the optos and they seemed to work fine. I'm aware that a bad diode could also be a possible cause but I'm not sure where to start investigating that. Interestingly, I also get errors every once of a while on switch 16. It will tell me to test that switch which will usually work fine when I test it and the error is cleared. I also notice that the trough stack switch is on the same row of the switch matrix as the #16 switch. Could these be related? Should I replace the diode on the #16 swtich? Other ideas? Thanks for your help.