Before I do that, I think I have all the pieces necessary to put them back together.
However, I don't think it's *broken* (sorry fixed title to better reflect that), I think it got too loose and the part came apart.
What do I do to put the spring back on?
EDIT: Shook my case several times and then I found the third part! Will try putting back together again. I have: the two main parts of the retention plate, the spring, the bolt, and the thin but tall screw where the spring should go.
The pin simply goes thru the center of the scissors and the nut threads back on.
The pin is only threaded on one end to accept the nut.
Same thing happened to me installing one last weekend.
Once you have it back in position and have screwed the four spring loaded pins in.
The textured nut should be hand tightened.