I've noticed that the volume of the amplifier fluctuates. It would seem that the eq does as well, but it could be just a subjective effect of the volume fluctuation. The volume fluctuates between a bright sound that seems appropriately loud (for the volume knob setting) and a darker more subdued sound. This problem has existed for about 2 months so I'm no longer sure which one is the true sound. The problem is not always present. Sometimes, on switching on the amp the sound is stable for a long time. Something that does seem to precipitate the problem is touching the knobs (volume, eq and reverb). There is definitely some scratching on turning the knobs. I live in a place where it rains for at least 5-6months straight. It is hot and quite humid at all other times because it's only about 10km from the sea. I'm thinking that this is quite probably related to, if not the cause of the problem. What exactly could the problem be? Is this something I can solve by myself or should I take it to a shop to be repaired?