[morzh]

Wire-wound is easily told from graphite. It is, well, wire-wound.

Yesterday I bought the D5S-6 DeoxIT and opened up my volume control.
As I don't have any Varsol, I used some undiluted isopropyl alcohol to clean the surface. The Q-tip came out fairly black each time (alcohol does not dissolve graphite or the substrate), so at some point I stopped, and re-measured the resistance of the scale, and it did not change; so I applied DeoxIT, one short small blast, worked it with moving the regulator back and forth, waited, applied a second blast, waited few minutes for it to dry a bit (it won't dry all the way, no matter how long you wait).

Then, as I was told by Codefox, I mixed some WD40 and Lithium, and with a toothpick applied a little and worked it moving the wiper.

Then I re-assembled the potmeter.

Result: for the most part the scratch (it was not egregious in the first place) has disappeared.
However when cleaning, I noticed that the part at the one end of the scale (minimum volume) is fairly worn down, showing discolored large spot, where the graphite is almost absent; this part still produces scratch, and no amount of DeoxIt, I think, will be able to remove this.

That's fine with me.