problem with volume control on a tube headphone amp


I have had my headphone amp now for about 2 years and have enjoyed it with no issues, added a turntable to the mix about 2 months ago and have been using it more and more as things burn in (tube phono, new arm, new cart, interconnects) and have put about 60 hours on the system since the added turntable, about 5 weeks ago I noticed that when I turn the volume all the way down the left channel still played ever so low but still played, now within a few days it has gotten louder and now is louder when turned all the way down than I care to listen to if I was adjusting both sides myself. I was wondering if spraying some contact cleaner or wd40 into the switch/control would be a good place to start. I have the amps bottom removed and do have good access to the piece in question. The amp is a Yamamoto HA-03 and out of warranty. If this doesn't work then would the next step be replacing the volume control or is there something obvious I might be missing. The problem is on both sources, turntable and CD. Thanks for any input.
tooblue
Post removed 

+ Elizabeth


also:

do not put WD40 I electronics period (wd40 is a cleaner with a mild lubricant not really good for anything imo). use a proper electronics cleaner. Also should note most volume pots are not very closely matched at their extremes ( fully off or fully on), you could have a bad volume pot too though.

it may also be you have to much gain in your phono section (CD) do you have gain adjustments so you can lower the phono stages gain? I know you said both cd and records so may be reaching there.

@elizabeth , swapped tubes right off to no satisfaction. @glennewdick, thanks for that on the WD40 and I will use a qualified contact cleaner.
Update. Cleaned the volume pod with a good electrical contact cleaner and let it sit overnight to dry out, plugged everything back in this morning and gave it a try. Results were not good, problem still there, seems that the left channel is at a fixed volume of a little louder than I normally listen and the turning up of the volume just increases or decreased right channel. Amp still sounds really sweet so I guess it’s time to find me a tech to work on it and look for a good used or cheap replacement till I accomplish that, thinking about one of those Chinese headphone amps on Ebay, any suggestions? Headphones in rotation are Hifiman XV2s, Hifiman HE560s and a pair of Audeze LCD2F. Thanks for your input
Question is this problem just with your turntable or with all sources?
@jond , both soures, CD and phono.
UPDATE. emailed Yamamoto and he sent me the part # for the ALPS control that he sources from Mouser Electronics and it is on its way. I am a fairly hands on guy and believe I will install this myself, wish me luck.