Casio SA series feedback

[Rolbista]

Hey all, first post here. I hope I'm not doubling anything. I have a Casio SA-65 and I usually run it through a Fuzz Face clone which sounds nice, but I thought it would be cool to add some internal distortion to the fuzz sound. The problem is that the usual feedback mod found at Casper Electronics oscillates at all times, even when I'm not playing which to me defeats its purpose. I tried using a bigger pot to get more range, but that didn't help at all. What I also tried:
- pin 6->500k pot->pin 1 on the AN chip. I didn't do anything except for cancelling the sound through most of the pots travel
- pin 6->pin 5 pretty much same as above
- pin 1->pin 5 on the AN - the same result.
Maybe a pair of back to back diodes in the feedback loop like in guitar stompboxes would be a good idea?
So I was wondering if anyone knew some other ways of getting a more controllable feedback. I am also considering making an FX loop beetween pin 5 on the OKI and pin 6 on the AN and use a second fuzzbox before the power amp.