In such cases, the only remedy is replacement.

... or if that cant be done fitting a fixed R to the wiper and ground or one
of the other terminals.


That will modify the 'law' of the pot and change the wiper position for most
settings. If the track is worn in the area that is most usually used (not
surprising!) moving the operating point to a relatively unused section can
work.

Fine as a diy work around but not worthwhile if a replacement is to hand as
that will give a better guarantee of a long term solution.


And do check that the electrolytic cap thats supplying the pot or goes
from the wiper onto the next stage is connected the right way around as
I've come across them connected arse about face sometimes;!...
--
Tony Sayer