hot Tubes

i just bought an old electro harmonix hot tubes overdrive which i think is the original model with tubes inside not the reissue without tubes,but ill need to check inside so see. Anyway i think the actual sound off it is very good but however sumtimes its crackling and is making noisy hum sounds. Does anybody know what the problem might be and how i should fix it. Think i might have bought it on its last breath.

[font=trebuchet ms]The usual suspects are power supply filter caps and the tube(s).[/font]

thanks man ill check them

I think you answered your question when you said "old". If the amp is truely old... then there are a number of things that it can be. With newer amps, if you experienced the same thing, you would expect it to be a problem in the tubes. With older amps... other things can come into play. Such as bad pots, faulty connections, and bad grounding connections. Check the wiring to make sure it looks fairly clean. If it looks pretty ratty... then your problem might even lie within the wiring.

oh yeah guys i forgot to mention, its not an amp, its an overdrive simulator pedal by electro harmonix

[font=trebuchet ms]All of the above still applies.[/font]