My MOT spotwelder:
http://www.mwdropbox.com/dropbox/MOT...rPrintable.pdf

Very nicely done.

A long time ago, I worked in a shop where the products were housed in deep-drawn steel cans. The covers were soldered in place with a big soldering iron. To open them for repairs, they were clamped between carbon blocks connected to a rather huge filament transformer.

I was wondering whether a similar setup could work for the OP, with the MOT clamped to the assembly near the braze area. Resistance, rather than induction heating.