MS-20 Kit keyboard CV has gone all wacky!

As I know the CV from the days it worked, which was
C1 1.00V, C2 2.00V, C3 4.00V, and C4 8.00v From earlier notes.
+/- maybe .01 on these but quite close to log CV.

Now I get 1.17, 2.18, 4.19, and 8.20 respectively.
This sounds like hell!!!

It had did this before and I stored it for 6 months and it got better.

But now after months of working I retired it for a month and
now I am getting the settings.

It is like a about .2V offset to all the C notes.

Any idea which bushing hides the CV value adjustment?

puzzled in Sarnia.

It sounds like you’ll need to adjust the oscillator scaling, and I don’t know where that trimpot would be. The service manual only shows the schematics, and the trim pots are not labeled for what function they control. I would think documentation came with the kit that tells about calibrating it. Did you get anything like that? We haven’t had one of these here, so I don’t have an actual unit to refer to.

I was given this to work with:

But what is weird that sometimes if I leave the MS-20 on the shelf for 6 months
its tracking returns to normal. It happened last time. This MS-20 was built from a kit by me back in January 2016.

It is a weird issue and this MS-20 has never left the house.

If it is still out of wack after another while of being stored I will do the adjustments.
This issue came out of the blue.
The reason I let it sit so long is that I have other synths to play with while it sits in the “penalty box” :>

Left it for a few weeks with no repair to the tracking, and now the
tracking works 1.0V to 8.0 volts as specced.
I did nothing except store the synth for a few weeks.
An intermittent keyboard tracking issue!