First thing to check is the flipper button switch on the cabinet. Make sure it’s got a correct gap and the points are not blown out. Next thing I would do is reseat the connector on the board. This might help, but there is a good chance you need to re flow the pins on the board because the solder cracks and doesn’t make a good connection. Here is a picture of the back side of Bally AS-2517-22 solenoid driver board. If you zoom in on the picture you can see the solder is cracked on the two pins with the wider traces going to them. Re flow the solder to eliminate the cracks

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Those two pins on the picture I posted are positions 8 and 9 on J1.