Hey guys, I'm trying to resurrect a Hermes Ambassador Electric with powered key action (not just power return). The problem I'm running into is that the power shaft that runs underneath the keyboard is jammed solid. It's supposed to be driven continuously from the electric motor, but it doesn't budge. The machine's reasonably clean and I don't think it's rusted up. What's the best way to free the shaft?

I'm hesitant to use isopropanol, mineral spirits or sewing machine oil because it looks like the key assemblies have cork or plastic in them (as some sort of clutch mechanism) I don't want to harm those sensitive materials. Are those materials indeed used? Can anyone tell me more about the mechanism works?

I tried applying some light force in back-and-forth motion to see if I could rock the shaft free, but it's not moving.