i've been using a blackstar ht-dual pedal for fours years now and i've been noticing that i'm losing volume on both channels. Usually I would match the clean volume from the amp in both channels on the pedal by turning the volume on both knobs to 12 o'clock. Now I almost need both channels to be at maximum volume to match the clean signal on the amp. What is happening? Is it the valve? Or is it something else like needing to clean the circuits of the pedal...? I dunno... Any suggestions?