that is an interesting one Mancini has , maybe someone finally smartened up and made a pin to hold the buttons together and not have the retaining pin break keeping the buttons in place if you pull the axles,. I bet the other end of that countersunk pin has a counterbore in it and once the piece are installed you peen the counterbored end to keep the parts in place ? I'm guessing this may be what you have from the description of what you are seeing ?

Frank can you grab the pins with 2 pairs of needlenose pliers and turn one while holding the other still ? if so it's going to take a little more effort to get them out.