In alt.home.repair, on Sun, 21 Feb 2021 20:36:04 -0800 (PST), Theodore
wrote:

Holycow! It's a self-closing hinge?! I never knew that. None of the pins were ever installed in it. Thank you all very much for the insight and the advice on how to stop the squeak.

I guess it's needed oiling for quite some time!