I'm considering putting my old bellows back on. This is what one of my old bellows looks like. Both are not bad apart from the metal/asbestos collar of which only one out of four has survived. VWH and JK now supply rubber collars, but not metal. Does anybody supply anything closer to original but with an asbestos substitute?
I'm not very confident that putting in a metal collar against a plastic outer with no heat insulation is going to last that long. Here's an idea. I've made up a collar from tin plate - original is 20 thou., about the same as a Waxoyl tin. Then wrapped with woven fibreglass tape .