Hi, over the years (40 years) I had problems with these double switches whereas the mechanism stopped functioning., it's like it worked for 40 years and suddenly it decided I had enough, and it stopped working.
there is a simpler and more efficient way to make them work: a.) you don't need the thin plastic lever to turn the tongues left to right, b.) and this lever is attached to the main plastic lever.
my simpler version (removed 3 movable parts) is, I've cut a thin cardboard strip folded it in 2 and superglued it on the inside and the outside to make it sturdy, I than filed it down to a smooth surface., drilled tiny holes and inserted it., you still can fit the underboard parts to the turnout,
my version, you couldn't use it with motors attached to the turnout, mine would only work with motors attached to the underside of the board (servo motors)., this way they'll last for another 40 years.

I haven't used that double switch as yet but it would be like any other turnout just drill a hole and insert the rod into the moving bar., of course I have to drill a small hole into it