I tend to agree that the 11R is not to blame, but this is going to require some serious intervention to solve. If it were me, I would be turning everything off. Then disconnect and remove the Control24 from the setup. Turn it over and remove the bottom panel and look at the circuit board that holds those controls. Locate every multi-pin connection on the PCB and pull/reseat every connection(at least 6 times). Doing that should scrape thru any oxidation buildup on the pins and sockets(remember that this is the same "vintage" design as the 002, which has the notorious power harness issue). Adding in some good contact cleaner to the process is also a good idea.
I would also trace back to the PSU and if that has a direct connection to the PCB in question, reseat at the PSU too
