Total Recall DMM feedback usability questions

[pietro_moog]

Hi guys. I built a Total Recall DMM, and it sounds good.
I still have troubles with biasing, but i think i'm getting there.
I have a few questions though:
1) my feedback is unusable over half. is this normal? what can i do to fix this thing?
2) when i add modulation, like over 1/4, the feedback knob reduces his usability to 1/3, then it goes straight into oscillation.

are these behaviors the normal thing?
Thanks guys