Vortex Sound Research

I already posted in the no stupid question thread, but no results so I hope it's okay to post it here aswell for more visibility.

The second oscillator of my korg ms20 mini is acting weird, it reacts to knobs of the first oscillator but not to it's own, I have taken the synth apart to see if there is anything unusual about it, but with no results. Anyone stumbled upon this problem and know the solution to it? Here's the problem demonstrated

Thanks