I just broke a drawer pull on a family heirloom desk. The pull consists of a cast brass base with a tab sticking out. The tab is bent down through the ring, holding it flexibly captive. The tab is about 1/8" wide and half that thick, the ring about 2" diameter and 1/8" thick at the tab.
The tab broke where it was bent, so the easiest way to line up the break is to put the ring back where it belongs and solder the broken tab back in place. If the tab is soldered with the ring out, then some bending will be needed to put the ring back. That seems a good way to break the tab again.
If I can find something to coat the ring pull, so the solder won't wet it, I think there's a decent chance of success. I don't think lead-tin solder will be strong enough and I can't think of a reliable anti-wetting coating that will stand up to silver soldering temperatures. Aluminum foil comes to mind, and might work for soft solder but I don't think it'd take the heat needed for silver soldering.
Thanks for reading, and any ideas.