Next I got stuck into the MPU board, on inspecting the pin headers I found the cause of some problems I was having with digits going out, which I initially thought would be the connectors. Some of the pins had bad solder joints. The pins were tarnished and had at some stage been sanded so I just replaced the pin headers.. no point in mucking about with dodgey connector pins I always say!! While I was at it I soldered on some long wires to where the memory battery connects to, and on the other end I fitted a 9v type battery snap to connect onto the battery holder that is shown in the second pic below.

These pics show the board installed and the 3x AA battery holder. Actually it’s a modified 6x AA holder. I soldered the diode into the backside that stops the MPU from trying to charge the alkaline batteries that will be fitted.

Still to be done, the ball shooter assy to be rebuilt, and one display with damaged segments to have a new glass soldered in. Also I’ll check and replace any corroded/tarnished connector pins.