What a mess! I suspect when the cockpit got a little springy, the boatyard (Burr Brothers in fact - their name is on the aluminum plate) installed the aluminum plate and glued it all back together(early 90's my guess).
I haven't tried disassembling, yet. Any thoughts on best approach? I thought I would try some heat. Even the through bolts are all stuck fast and won't turn out. I thought I'd try torch and heat gun to loosen the 5200. No too worried now that it is in the shop. I could burn it off.