Dead Keys on Roland RS-101

I was lucky enough to purchase this 1976 Roland RS101 for a steal ($150) !
Though there were 7 dead keys in the bunch.
I thought I’d take a look under the hood… contacts seemed to be fine. Though there were a few dead transistors that I replaced for the individual keys…Still nothing… It’s not detrimental to my playing - but I would like to have it figured out !
If anyone has any ideas on how to solve this polyphonic analog string emulator problem I’d be happy to listen and try my hand at fixing the issue!

Hey,

I don’t know if this applies to your one but when I had a dead key on a string synth it was one of the op-amps that amplified the key press signal.

I have an RS-101 with a similar situation. Not fully “dead” keys but one of the F keys and one of the B keys is very quite, almost inaudible, especially in slow attack mode. Since my other F and B keys work, I’m not sure what that says about my LM3216 chips, if they are OK, or might be faulty. Any pointers on how to isolate where the problem is being caused would be much appreciated!!