Vintage Synth Repair

I have a 490 too- I think the biggest problem with these things is the
crappy slider potentiometers in the control panel; I suspect that y'r
problem may be in that area. mine's ok at the moment, but a crumar
performer of similar vintage (& isn't there some family connection
between elka & crumar? weren't the founders brothers or something?)
has had to have all of it's sliders replaced because they were going
crackly or open-circuit.
it would usually be something like this on these machines- they're not
especially complicated circuits, & are reasonably robustly constructed.

duncan/r.m.i.