Dirtbag Squeeling

[hewie]

Hey guys, built the Dirtbag last week, and everything seems to function fine, however after about 5-10 seconds of have power connected to the pedal, it starts to squeel/screech uncontrollably. If the blend is set for dry signal only, no squeeling, but any adjustment of it brings in the painfiul squeeling. The first handful of seconds when the power is connected, the delay works as it should, but then the squeeling fades in. It's kinda like its feedbacking. I've replaced every IC, a number of resistors and capacitors so far, and tried different power sources (9v regulated, 9v battery, etc). The gain trimpots don't seem to alter it in any way. Clearly I'm missing/overlooking something.

Any suggestions where I should concentrate? Much appreciated.

On a positive note, built the LowRider earlier and it's fantastic! Moving on to the Current Lover 

[hewie]

Potentially found the issue at C20. Replaced ceramic with film, and seems to have removed the squeeling. Odd