So when I took ownership of my Sei it didn't have a preamp, so I bought a Bartolini and had that fitted.
It has a push/pull control on the volume control which acts as a passive/active switch. The problem is the depth of it. The push/pull control is ever-so slightly too deep for the cavity. The bass has a back plate that's made from the cut out wood of the top of the cavity, which must have taken ages to make and obviously looked beautiful. The guy that installed the preamp had to make another backplate from plastic which is slightly thinner, but is still actually slightly too thick, there's a slight bulge.
I want to start using the original wooden plate.
How easy is it to replace the push/pull control for a standard volume control, doing away with the active passive switch?