Feedback from Sproing Deluxe Reverb

[GuitarZero]

I built my Sproing Deluxe and love it on a clean amp setting on a Boss IR-2. Unfortunately, if I leave it enabled when I go to a higher gain amp, I get a high-pitched whistle that I'd call feedback, but can even occur when the guitar volume knob is all the way down. What can I start looking at?

 

[Feral Feline]

Your camera.

Post well lit pics of your board, front and back with enough focus and detail to tell what colours the resistors' stripes are, wiring, etc.


Look for solder-bridges, cold solder-joints, make sure all the components are the correct value...

 

[GuitarZero]

I wanted to circle back and say this problem is elsewhere. It surfaced initially when I added the sproing to my chain, but today I tried again with the sproing removed and ran into the same issue. I think it's an iffy connection on my line selector pedal. Playing with the cable (brand new EB flat patch cable) in that input caused it to occur/resolve.