Question about tubes.

I put new tubes in my blues deluxe reissue a year ago. It stays at my rehearsal space and I have a practice amp at home, so I only play it once a week.

The pre amp tubes are Tung Sol 12AX7s

The power tubes are Winged "C" 6L6GC

Last time I played it I started hearing a muffled sound to the tone. It doesn't muffle the volume just the usual lush tone it has. Could this be the tubes going already?
More likely to just be dirty. And more likely to be the input socket than the tubes. Buy a can of contact cleaner. Spray some liberally onto a plug and work it in and out of the jack a few times. ie. you are using the plug as an applicator.
You can do the same thing to the tube sockets too if you like only using a tube as the applicator. ie spray it on the tube pin.
You need proper contact cleaner (Deoxit is a good one) NOT WD40.
I assume you've already tried a different cable, no?
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