Ultra Flanger Noise

[Bassisst90]

Okay. So I'd built the Ultra Flanger a while ago and it works pretty well, but I seem to be having a strange problem with the effect. The flanging works fine, its just that If I turn the regen pot from 3 o'clock on it gets this intense oscillation. I don't know how to get rid of it. I tried adjusting the trimpots but that didn't seem to help. Anyone run into this problem?