One of the bridges is made of discrete diodes on the top side of the board (circled in red below). The wrinkled appearance is not a problem, many will look like that, in fact I think all the Bally games I had looked like that. What usually is a problem is all the through holes. The lands around the hole crack, or around the leads, sometimes not easy to see. The usual fixes involve jumpers over bad traces, plus there should be additional jumpers added to this board as described on the pin repair sites to increase reliability. Plus all the male pin headers on the board should be replaced. The bridges should also be upgraded to higher amperage.

In short, for a small amount of money you can buy all the parts to overhaul this board and spend a good day or two, depending on your experience level and overhaul this board. It's not really much more expensive to buy a replacement board and be done with it - if you so desire.

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I know that...just answering his question why he saw only three bridges compared to the schematic that shows four.