I did some investigation, and the old jacks are unobtainum.
After some research, the individual connectors plated in the metal of your choice are the way to go.
The specs on the connectors that will work with chassis isolation, ground to board which grounds to chassis, are almost non existent too. This leaves you with do I trust the vendor, which is where a lot of these hunts seem to end up.
I purchased a bunch of the better gold plated ones from Parts Express and similar or the same sold by others. One of the comments that seemed well informed stated that the insulators were Teflon, so hacks like me won't melt them when soldering. Might be $6 for 2 connectors, you can go on the auction site or others and get the "good ones" with no specs for $1-2 ea with quantity. Nylon vs Teflon for the insulators and thickness of gold plating are issues along with core materials.
Check out CMC Charming Music connectors from Taiwan.
The connectors fasten to the rear bezel from the inside which sucks, why, because you can't them loosen them from the bezel without de-soldering them. The pcb board has almost all of it's parts accessible for soldering from the bottom, but not all, so in a recap or relay the board is coming out.
Plan B. leave enough slack in the replacement wires to the connectors that you can unscrew the bezel freeing the pcb board from the chassis when you unscrew all the little bits and pieces. It's plan B.
The three new gold plated connector pairs will have to be de-solderd at some point and redone with longer flexible wires.
I installed an extra screw in the chassis next to the Ground Label on the rear bezel, the old modular 6 connector for RCAs also had the chassis to PCB wire built in.
I think I paid $75 for this pre amp, and almost works perfectly.
Some of the lighted switches are still gummed up, so more DeOxit or pop them open. Time to take the front off, again......