Well...great news!!! The Cross Bolts are in
Having not done this before, and reading everyone's advice (especially BoyWonder), I figured it out. I'm including a few pics from it.
I supported the corners with hydraulic car jacks (I happened to have a few) and blocks of wood with rags to protect the ceiling.
Used a come-along clipped into one of the holes in the metal guides and also clipped into the end of the spring's circular metal loop supported by a cam strap (in blue in the pics). Added tension to the spring thus being able to unclip the metal chain.
I took out the bolt assembly that allows the cross member to slide in it's guide freeing up that cross member's arm.
With this free, I was able to pull the cross members together and thread the new shoulder bolt (McMaster Carr) through. I also added a nylon curved spacer (McMaster Carr) into the assembly as well.
Reassemble the cross member into it's location, pull even more tension on the spring to allow the chain to clip back in around the hook, then release tension to allow the system to adjust.
Remove the cam strap and voila...things are back to normal.
Tested the top a few time to make sure all is good.
Thanks again everyone for your advice.
Cheers