Look here: Jess Oliver's legacy - AMPEG PORTAFLEX CLUB part 12
If you look at the next couple of pages in the tread, there are more details concerning the metal corners.
Wear protection on you eyes. It is easy to have metal bits fly off if the pry bar slips. Sometimes there is rust on the nails which anchors them into the wood. Be patient. If you are doing a restoration, often you can clean the nails and reuse them. Otherwise, vintage corners are available at www.fliptops.net
. The replacement nails are not the same.