Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Weeden was famous (read as INFAMOUS) for using lead alloy castings for many of their parts, and thus many of those parts are no longer with us for reasons as you just found out!

The bad news is that it is rather unlikely that any of those parts are just laying around out there looking to find new homes. The good news is that carving a pattern and casting yourself replacement parts is at least possible. Or even just carving one out of a hunk of lead can be done.

Don't know for sure whether that fitting was threaded into the boiler, but I highly doubt it, and expect that it was simply cast/fused into the boiler, or keyed into it in some fashion.