As Quench says, job 1 should be to replace the J3 connector. Those original IDC type connectors are pretty much one and done so I recommend ordering a new KK style rebuild kit.

Big Daddy's eBay store is back up and you can get a complete solenoid driver kit from him. You can visit his store here: ebay.com link: str

Kits to order:
ebay.com link: itm

And you should replace the original filter caps: ebay.com link: itm

I'm not sold on rebuilding the entire board but I do recommend jumpering J3-25 to pin 13.

Until you get the 5v operational its a good idea to hold off on installing the new MPU.