Re: So I found this 5-chime...

John,
Looks like you have a fun project going there.
Remember, as stated before, don't use a regular pipe wrench on any of these parts. The teeth will leave permanent gash-marks in the metal. Use a wrench with flat surface jaws, and be careful that it doesn't slip off.
Since the valve portion is screwed into the base of the whistle, rather than being an integral part of the assembly, if you find that it is too far gone or parts are missing, you can replace that entire valve with another one. You'll need the o-d measurement and thread size of the pipe going into the base of the bowl to get one that matches. They can be found on eBay and at steam-oriented flea markets such as at steam tractor museums & shows.

Can you post another shot of the whistle looking directly at the top center of it?
And please keep posting here with your progress, including lots of pictures as you get it apart.
Thanks,
Steve G.
eastern PA.