OK .. any ideas anyone ??? My 2nd Lady Luck (which is presold) is busting on 20 instead of 22 or above . I have checked the score reels are correctly reporting 20 , 21, 22 etc . I thought it might be that the 10's card reel was reporting it was on 30 whehn actually on 20 etc but no luck . The only thing I can find is that when the 20 relay is tripped, the reistance on the earth lug of the coil for the bust relay drops from 4.6 to 3.6 ohms (and if the bust relay is tripped the resistance goes back to 4.6 ohms)
I can't find anything else wrong in the circuit (see circuit attached) .

Any ideas anyone ? I have spent way too much time chasing this fault already . I can't sell this game to my cousin till I sort this out and really want this game sold and out of here ASAP.

Any help much appreciated.

Cheers
Dave