I have Bally machines which I am currently restoring (separate threads will follow in the near future). As I have had issues with some of these power supplies (ie. rectifier boards), I knew I wanted to address this once and for all with a rock solid solution.
I did consider restoring the original board and replacing components, but must admit I was not that keen to with all the desoldering (especially the header pins). Plus, although the boards themselves seem in OK condition, I have read that the original boards (excluding the components) were not the best designs. As Clay has recommended mods to these boards, plus component upgrades, this tipped the balance in my mind to explore alternatives.
So, in the end I decided to go with the Bally rectifier board replacement from Great Plains Electrical (GPE)
http://www.greatplainselectronics.com/proddetail.asp?prod=135-104.
For $60 you get a completely built board, plus all the 3 connector housings and molex connectors, standoffs, etc. The link above has the details. The only work to do is to remove the transformer wires from the old board, and (carefully) re-attach the wires to the new board. I have completed all 4 games, and must say I am 100% impressed with these. I believe the $60 is well spent, and I am confident I will not have any power/connector issues with this part of the backbox.