Don't know how, but the insert fell out of a St. Croix Avid rod tip top.
I called St. Croix and, since I had spent five minutes registering the rod after I bought it, they sent me a replacement kit at no charge which consisted of tip top, glue and instructions. Glue comes in powder form these days (years ago it was a stick you melted) and all you do is stuff the base of the tip top with it, heat and align. You can (carefully!) reheat to realign if you don't get it right the first time.
This rod was back in action in 10 minutes.