I bought a Williams M727 small bore trombone at a flea market in Aloha Stadium, Honolulu 36 years ago and was hoping someone might have more information on the age etc. It has a very indicate tuning slide with an arrow head a screw mechanism for adjustment. It has a Metronome in Honolulu label on the case. It looks old!

Pre-WWII, but not by many years.

Check out Robb Stewart's article on Williams:

https://www.robbstewart.com/williams-history