I have a tube amp and my pedals are: Dunlap Volume pedal plugged into korg tuner with one line out. The other line out from the volume pedal goes into ibanez tube king pedal into tc electronic corona chorus into electro harmonix hum debugger into tc electronic flashback delay into amp. Once in a while the volume will just drop way down. It will eventually come back up although it seems to come back after I mess with all the buttons on my pedal board and tug on all the chords. If I pull out of my pedal board and go direct into my amp, the volume seems to be fine. None of my pedals are battery operated and the chords seem ok. I don't have active electronics on the guitar. Any idea what might be causing this?