The message .com
from "Eusebius" contains these words:

Thanks - If the nipple's dropped out will I find it on the floor
underneath or do I have to get another - if so where? what does a
nipple look like - is this the technical word to ask for? Andy

It's the tiny jet through which the gas emerges. The combination of the
size of hole in the jet and the pressure behind it are what determine
how much gas comes out. If there's too much then that would cause the
problems you're seeing. It's unlikely - they don't often just "drop
out". It'll be a small metal threaded cylinder with a tiny hole through
the middle. Rather like a radiator's bleed nipple in size.

--
Skipweasel
Pay no attention to the man behind the curtain.