I decided to slowly increase the temperature of the new one I broke into. A
bit more subtle. The cross-bar is probably lead and just the ends , soldered
to the wires are Woods or low temp solder. The grease turns to oil at 80
deg C or so.
In the core is a strip of silicone rubber foam , doubled over. When the
joint fails on the foam pressured end , it fails at that end , and then
"hinges" quite neatly at the othe rend , that is equally softened but
without the foam pressure. The temp then goes down, in normal use, and the
lead bar is then held in the open posistion.