Is the light turning on (on the Servo Controller)?
I have had issues with other equipment where the PS is working but not providing all the power per specs.
You could change the power port for a modern locking version.
I suggest you post your concern on the FaceBook Vintage Infinity Group. Lots of knowledgeable people there.
Some info: http://www.infinity-classics.de/technik/manuals/RS_IIA_technical_sheet.pdf
https://www.davidsaudio.com/rs2a-b-manual.pdf