My Surfer board was basically a cardboard surfboard with delusions of grandeur.

The bit about your wiggle being the wood sliding on the tang and not the screw hole really clicks for me. I spent way too long treating it like a stripped screw when the whole problem was the wrong part moving. That is the part that gets you, all that wasted time on a fix for a thing that was not even broken. Rubber squishing into the gap makes way more sense than jamming wood in there. I will keep an eye on the tang for rust like you said, that is a fair point I had not thought about.

Heard a trick about tapping the caliper with a screwdriver handle to shake bubbles loose.