For my MFOS Soundlab Ultimate, I have to modify an old midi keyboard to use as a CV keyboard. I had to rip out all of the electronics, and replace the buttons and add a chain of resistors. I took a few pics to show how I accomplished that.

I also have another issue I need to solve. The plunfger on the new bunnons is too far from the bottom of the keys to get depressed as is. What I think will work here is attaching some craft foam using some JB Weld to glue it together. (I love JB Weld, it sticks to almost everything and is hard as a rock when dry. I use it in a lot of my projects.)