Quoted from Ranhorton:FYI!
I bought a few new buttons for my slugfest. They don’t fit. Total waste of money. Find NOS if you need new buttons.
I think I did this too. The originals were twist-lock style and the new ones were just press-in. I had to take them apart but was able to use all the new guts (colored part, insert, spring etc) and they worked great. Just sort of a pain in the rear.