While reading through some other sites I noticed CJ removed balance controls on some preamp versions. It's possible they compensated for this with resistors, different value potentiometers, or both.
Unfortunately schematics and parts changed on the fly for many high end brands of that era making it difficult to match up with your preamp date of manufacture and serial number.
At this point you probably can't go wrong with replacing with the identical part if it's served you well.
Or taking it apart and cleaning it.
Jonesy
"I know just enough to get into trouble. But not enough to get out of it."
