Here's one I never saw come up before. Went out to the boat (on a mooring) and the boom had fallen out of the gooseneck. Thank God it didn't happen under sail.

Seems the boom sits in a slot and is held in pace by  a pin that looks like a clevis pin but doesn't have a raised edge... it will slide all the way thru it's hole in the gooseneck. The only thing holding it in place is a thin carter pin inserted from the top, which I found broken off and laying on the deck.

I replaced this with a 3/8" by 3" clevis.

Might be something worth checking out.