I ground down to the screw heads outside and with some effort they turned out (also sealed with 5200). There is a 90 deg angle tailpiece (also installed with 5200) so I can't get leverage straight up. I tried sticking a pump handle in the tailpiece, only have room for about 12", pulled up as hard as I could, no movement. I will try the trick with piano wire, maybe I can get one of those wire saws used on PVC pipe around it. I don't want to heat it much, this is an epoxy boat which is all good except for heat - it softens at a much lower temperature than polyester. If the Antibond has a chance of working I might see if West Marine has some - I am here in rural Virginia, closest thing to the boat is a 7-11 about 10 miles away, then the Deltaville West Marine about 20 miles away . The seacock is tight to a G10 pad and I have not been able to get any sort of wedge under it. I might be able to get a saw cut under one ear and pry from there.

I don't have a problem with Marelon seacocks or 5200 - both of which I specified during construction. Installed right, I shouldn't have to remove them in my lifetime, but this particular one wasn't installed right. I intend to install a new Marelon seacock using 5200. Usually on 5200 you just need to get some force on it and it will creep slowly and let loose. In this case its a little hard to arrange, and being 3000 miles from my fully equipped shop doesn't help. If I was near home I would just design a little custom puller, CNC it up and Bob's Your Uncle.