I have a Yocto that I just finished (with a big break of 3 years

I have some problem with it.
On first power up and start seq immediately, on ~first Step the voices have a good volume, after, all voices volume is decreased
Bassdrum, Snare, Rimshot, claves, and handclap do not work (bassdrum ans snare have very low volume)
If i turn clockwise accent Knob, all voices volume decreased
I'm search, but is to hard to find, i have a doubt on BA6110, but I don't think this is the source of all problems.
Here are the pictures, if you see a few things : https://photos.app.goo.gl/oKS8EBhXQ4mAnXuz7
I can't find anything yet.
if there is someone who knows how to repair this machine and who could do it, PM me

Thanks.