I have cleaned the power connectors on both boards (the pins), they were really dirty. However the problem remains, and the machine is reseting sometimes. I activate the pop bumper by itself, and it will work fine, the sling shot will not fire. But if I knock some targets down and activate the pop bumper, the slingshot will fire instead of the pop bumper. Up until now I have been talking about the right slingshot. But I can also get the left slingshot to fire whilst activating the pop-bumper, by flicking the spinner at the same time. The little power board above the transformer (its a bally board actually), has rust near some solder areas, and I reckon it needs an overhaul.

I didnt clean the smaller connector pins on the MPU board, it that worth a shot? ( I did reseat them though). Now that its reseting I will not play it