i have a flash machine also, and the connector problems are non stop. I would first make sure all power supply voltages are within range, as they vary with line voltage. Secondly, and i havent done so yet, there is a re-designed mpu / solenoid board for sale out there that is one board, not two, solves the connector problem and other issues. sells for about $300.00 i think rotten dog amusements? íf not, you can buy a new set of connectors/pins for about $12.00 on ebay. if you dont know how to re-work a circuit board, i would recommend getting professional help on that. i will be buying one as soon as can afford one. P.S. replacing the vacuum scores with led scores is a very good expenditure!!! i also need to re-build my drop targets soon.....
good luck!!!