I am New to pinball machine restoration. I have begun work on my first table, a Data East "Back to the Future"

It is doing something that seems odd to me. Under normal play conditions it will load a ball, the switch that senses a ball has been loaded (in front of the plunger) senses the ball and all is good. The issue begins when the first Multi-ball gets locked in the multi-ball track. At this point, the machine loads the next ball and continues trying to load another ball until the balls are removed from the plunger area.

It is almost like the logic is reversed when it goes in to multi-ball locked mode. If you catch the ball when it is loaded, or immediately shoot the ball the machine does not attempt to load another ball.

Anyone have any ideas on this odd issue?

I have resolved the issue, turns out there was a short in the wiring that made any switch in that line of the switch matrix appear as all the switches fired. (Short was in a coin door switch)