same thing happened to me IN THE STUDIO! so myself and the engineer took the darn thing apart, took the pot apart, greased, lubed, polished, swore and still barely any improvement. then we put it back together, which was even more trouble (the kevlar string is a pain to put back).
i had to order a new pot from e.b. to fix the problem.
what's more, e.b. changed the pots they were using...new pot, different size, so i had to work around that. since your unit is fairly new, this shouldn't be an issue.