Hi I have a Bally blackjack 1977. the flippers work good most of the time but some times the relay on the solenoid driver board(as-2518-22) will start buzzing and the flipper will not work and the display will go nuts.. I have 2 other boards and they will do the same thing. some times will work for days with out buzzing. and one more thing. it will not do it for the first game of two. then it will start and no flippers display going nuts then it will stop and you can play for some time but it will start up again.

looks like reflowing did it no more buzzing. and the flippers keep working. but the display will go nut but you can play the game