I'm starting to renovate a TZ I bought and I'm scratching my head why the upper left flipper won't work. It's electronic not a mechanical problem.So far I've (1)removed the coil and checked resistance's and OK but subed another known good one anyway(2)Getting 68V on both outer lugs(3) breifly earth centre lug to siderail and coil fires ok. (3A) swapped flipper opto boards over(4)Remove flip board and replace TIP36,TIP102 and 2n4403(5)Flipper holds but flutters when trying to power up(5)swapped flip board out of Corvette and all ok so prob is still in flip board. Only thing I can find wrong is resistor R23 - 470 ohm is reading 1500. could this be the prob??? Amended--- PLS check next JPD post for more input - Thanks