I replaced the original fiddle block with the Garhauer block from DR Marine. First time out with it, wife and kids on the boat. We were sailing along all of a sudden THUNK. Pulled right out. Lucky for me my wife is an outstanding crew member and started dousing the sails right away, while I held on to the wayward sheet and tried to keep us into the wind. We got it all under control and motored safely back to the harbor.
So when I installed the new one, I had to tap the new screw holes offset from the old ones because of the orientation of the base, and the bigger screws. The only thing I can figure is, and I really hope not, that when I took out the old screws out the metal plate on the under side of the CB trunk fell off, so my new screws were just threaded into the fiberglass. But I didn't hear anything fall when I was doing it so I don't know. The other thing is that the new screws that came with the new block seemed very short, like only about a quarter inch of screw coming out the base when the screws are in, maybe the metal plate is still there but the screws didn't reach it through the fiberglass. On the other hand when I tapped the new holes I didn't feel like I was going through metal, so I bet the metal plate fell off. No idea how I'm going to reattach it, probably have to careen the boat in my yard and go up through the CB slot, but I don't know I would get it back to where it goes.