This one is already fitted with a sheet of thick felt under the buttons to help this. The sticky button was actually more because of a slightly bent spring, that didn't really push the button back in place. So maybe "sticky" is not the right word
However, I am thinking of maybe raising the felt sheets a bit with some thin wooden sheets. Fortunately I have access to a lasercutter, so getting the dimensions right should not be a problem
As I mentioned, I am not planning on selling it. I'll give it to my niece, so she can see if it actually is something she wants to pursue. If she doesn't stick to it, I'll gladly take it back, since it's such a curious little thing. And if the mechanism breaks eventually, I might try and turn it into a digi-tina at some point