[Richard]

Alan,

I can tell you about the latest technique and materials I have tried, that are holding tight after three years.

Take a sharp pencil and mark the door and frame for reassembly.
After I got the skin off the door, I removed all the old VHB tape with 3M adhesive remover. I then wire brushed the mating surfaces with a wire wheel on a side grinder. It leaves a rough surface, on purpose.

I then use 1 inch long strips of 3M double sided adhesive about every 8 inches. This is to act as a spacer, and stabilized the skin while the epoxy is curing.

I applied a bead of Jamestown Distributors Thixo. Easiest stuff to work with ever. Put the frame and door together paying attention to alignment marks.

Clamp very lightly. Wait 24 hours.

After looking carefully at the failed joints using the Gflex, I realized that the clamping I had been doing was squeezing the epoxy out of the joint. I was using wood working thinking where more force is better. That is not the case with the skins. Light clamping, the thickened epoxy, and the double sided tape ensure the epoxy stays in the joint.

I then went back with the Thixo and ran a filet around the joint. I smoothed it out with popsicle sticks.

This approach works better than anything I have tried.