korg Volca bass vco pitch 2+3 issue

[cake101]

Hi
I turned on the Volca Bass for the first time in a while. Using the plug with no batteries.

I played a note and turned the VCO pitch knobs. 1 works as normal, but 2 and 3 do not. If I turn either way, the pitch does not follow the set tuning. Sometimes it will at the +12 mode on 3. Sometimes I turn the knob to the end, and it is out and drifts by itself, say a 1/4 step. The OFF position varies too. Rarely appears on the screen in the 12 o'clock position.
The numbers on the screen are all out of sync too as a result..
I also left it on for a bit and no difference.
Anyone have any ideas what this is or what I could do to fix it?
Here is a video:
When my finger points it is showing where the centre of the pot is placed in the off position which should be the 12 o'clock position.

https://flic.kr/p/2mEQokB

Cheers.

[LM]

You should search for the Volca Bass Service Manual, it has some testing procedures for checking the range of the knobs, including VCO tune 1,2,3.

Also make sure your power supply has the proper voltage, I noticed that tuning on my Volcas gets really weird if I run them on low batteries.