Well, whoever the cab builder was, they did you a bit of disservice by not color-coding the +12V and -12V rail feeders. Hopefully there's indications marked on the backside of those distros (which, I should note, aren't too shabby...they've got filtering, for one thing), otherwise you'll have to figure out their manufacturer and then chase down the board info.
Once you figure out the two 12V rail polarities, I'd strongly recommend yanking the RED wiring for one of those rails and changing it out for some other color to avoid this issue in the future. But as for P/Ss that'll work here, I'd suggest going with this: https://www.newark.com/solahd/sld-12-3434-12t/power-supply-linear-12v-40-8w/dp/93K6589 Yes, it's expensive when compared to switching P/S units, but with a LINEAR supply like this, issues with the P/S leaking crud onto your DC rails become a non-issue. It's worth noting that Synthesizers.com's in-case supplies are also linear, as well as some other makers; even my Kevin Lightner-built Digisound has a honkin' big linear supply in it...and if Kevin Lightner signed off on it, it MUST be the right thing to use!
Oh...and you get 3.4A per 12V rail. Now THAT'S a beefy supply!