I was able to gently pry the squashed edge of the rivet up. I used a piece of sheet metal to protect the blades & held the pin down with a small screw driver. Worked my way around rivet several times with my pocket knife. Then I pressed down the blades from the opposite side with a small fender washer, rivet in the middle. That gave the one blade enough room to move freely. Works like a champ.
Thanks for all the suggestions.