Hi all,
It has been a while since I looked at the piano hinge but I think it is very similar to what we sell. On those there is a detent in the middle of the hinge to keep the pin from sliding out.
Take a look at this picture (not a very good picture as I used my phone
). Just to the right of my thumb you can see where the manufacturer punched the hinge.
Bruce I'd check your hinge, maybe they forgot to "punch" yours, or maybe it wasn't hard enough. But If you take it off I think you can do the job yourself with a good center punch and a hammer...
Keith