Thanks to you guys I was finally able to get this done! Just in case someone else runs into this issue, here is what I did:
1. Screwed the flange into a 2 x 4 with some 1 inch screws
2. Hit the stuck joint with PB Blaster
3. Inserted one of these internal pipe wrenches: http://www.amazon.com/General-Tools-139 ... 743&sr=8-3
As a tip: to use these, I found you have to stabilize the moving cam with a small screwdriver when you first turn the hex portion counter-clockwise to gently wedge it into position
4. Used a box wrench to gently turn the internal pipe wrench counter-clockwise
On a somewhat related topic: Upon closer inspection, the chrome finish on the tube shows some age related scratches in the finish. I am considering replating the tube for cosmetic reasons. (I realize this kills the resale value, but I mean to use this table base regularly and care more about how it looks than selling it.)
1. The finish on the center tube appears more shiny than the finish on the legs of the base. Is this normal?
2. Does anyone know what type of finish was on the center tube of the P & L bases? Is it chrome or nickel?
3. Any advice on how to get this plated? I imagine the company just has to protect the threads right?
Thanks again for all of your help and advice!