I got the blocks off this weekend. It's not collapsed as thought, but ground off. The blocks are hollow and the edges of the blocks which were flat/rounded are kind of knife edged. The edges of the perches are sloped from the edges of the blocks grinding on them.

Pictures sometime...

Man, the evil of blocks is compounded by loose Ubolts. I ordered some spring perches and may look into replacing them when I have the welder come out and weld in the spring hangers.