Aquaboy Deluxe Distortion and Runaway Oscillation

[Nick LED]

Hello everyone, first time poster here. I'm hoping that someone can help me troubleshoot a 2013 version of the Aquaboy Deluxe that I'm finally getting around to building. It's the MN3005 version and I've made sure the jumpers are set correctly for the BBDs. D2 and D3 have been omitted as per the instructions. Component values have been double checked as well.
The main symptoms are extremely distorted repeats at all bias settings, and runaway oscillation with the feedback knob at only 1/3 of the way up. I've seen several threads where builders had a similar problem, but I can't find where anyone ever actually resolved it.
Did anyone ever find the solution to this problem? Or does anyone have any thoughts on where to start troubleshooting?
Thanks.