Success!
When searching the web for others with jumpy value-sliders(another fault I had on my esq-1) I found this thread:
https://forums.syntaur.com/t/ensoniq-es … und/448/13
“we_robot” suggested looking at U40 and it’s filter caps being 0.01 instead of the recommended 0.1. This is some fault from the factory, supposedly.
I replaced these caps and lo and behold, both the jumping in the value-slider and the noise are gone!
It is still gritty sounding, but when turning off the DCAs it is silent(in some patches I can still hear the filter clicking but I think that is normal).