Yes the MPU switches are set for the correct game, and all switches in the trough (and all over the play field) work perfectly performing a test sequence, plus I have checked every switch with a multimeter numerous times when the game freezes. I have also tested every diode.
Its a weird thing because the game works 100% unless a ball drops in the eject hole. Trust me the switch there is perfect as I have had a meter hanging off this.  For some reason after a new ball is provided, it seems like the MPU forgets the ball in the eject hole is there,,, if that makes sense.
Thanks....