Hey all, I'm hoping someone on here has some insight into this big-box chorus pedal. It's a DOD 690 Chorus, made in the late seventies I believe. I love the sound of it but it has started making unpleasant distorting noises, almost like a solid-state amp clipping but much harsher. I know next to nothing about solid state circuits or pedals so I'm not sure where to start! I also cannot locate a schematic for this pedal on the net. Any ideas what I should look into replacing?