[sdiy] Arp Axxe, Moog type filter issue

[Analog/DIY]

Hey guys, 

I have an arp axxe here with filter issues, it's the one with the ladder filter on the main board (no sub module VCF)

The main problems I am encountering are...

 The filter stops oscillating at low frequencies and the cutoff lags when the cv is changed. When is does oscillate, it's not a clean pure sine, on the scope the "sine"  sort of leans to the left.

Based on these symptoms, It makes me think there is some sort of high pass filtering going on in there somewhere, or there is some mismatch in the ladder or diff amp on the output. I just can't seen to track it down.

Any ideas on what might be the issue? 

Thanks in advance!

-Mike