It never hurts to state the obvious; in this case, I tried a couple of new 1M audio pots (both tested good with the ohmmeter). This whole thing is bugging me because, as a passive filter, it's SUCH a simple circuit (a total of three components, all of which have been replaced with tested new ones).At the risk of stating the obvious, is there a chance that that slider is just worn or dirty? Do you a see a consistent change in ohms if you move the slider from bottom to top? I just wonder if the strip inside inside is worn out.
There has to be something else going on here; I'll have to look around at the rest of the synth to see if I can find it.
~G