removed the bolts and it seems the aluminum corners have become one with the aluminum mounting posts extruding from the pontoons . tried liquid wrench but nothing. any other ideas?
I just removed the platform from a 1976 Hobie 16. That particular one wasn't so bad but I did have to use "persuasion" via a section of 2x6 for padding and pounding upwards with a heavy hammer on each corner gradually lifting it off.
If yours doesn't budge at all with some mallet blows (don't dent or bend your aluminum) then at some time your frame might have been epoxied to the hull (not pontoon) pylons.
In that case you'll probably need to use heat to soften the connection and expand the casting. Don't burn up your casting or catch your boat on fire when you are doing this, I've never tried it so hopefully others will have real-life help to offer.
in order to remove a casting sometimes it requires complete disassembly of the tramp frame. It is possible there is a build up between the casting and pylon. If it's a base like lime or salt distilled white vinegar will loosen it without damaging the metal. It takes some soak time if its really caked up.