A few days ago I started to notice an intermittent farting/buzzing sound when I hit certian notes. I went through a process of elimination and think I have isolated it down to my Boss TU2. I tried running it with a 9V or power adaptor, no diff. It is out of warranty, too. Anyone else have a similar problem with this pedal? It is about 1 1/2 yrs old. Worth bringing to a shop for repair? Or send it back to Boss?