SK-1 crashes when switching bend pitches

[pery]

Hello all, I'm new here!

I have a circuit bent SK-1 that began to be unstable recently.
I have a switch to play from 2 different bend pitches and I usually use it in the middle of a line or melody, to give a yodeling effect.

But lately it crashes very often when the switch is halfway between the two positions. either the sound freezes, either the drum machine starts.

My switch is 6A and I changed to a new one that is 3A. It's way more sturdy but with this one it gets even more surely crashed or freezed.

Did anyone experience that before, and do you think of any solution?

thank you all for your help!

Pery