I will occasionally get a screeching noise at the start of an overdub while recording....it happens on playback; it is just at the beginning of the loop, but I can't seem to eliminate it....any suggestions?  It seems to happen while I am using my FBV Express Pedal....I will record the first loop, and when I do the first overdub is when I hear it.  The only way to get rid of it is to erase the entire recording (not just the last overdub)