My buddy in Seattle told me to use a 3/8 inch wrench for the bolt on my Kirby Morgan hat, but it was wrong.
He swore by it for years, so I tried it on a job last week in Portland. The wrench slipped, rounded the bolt head, and I had to surface early to fix it. Turns out the manual says you need a 7/16 inch for that specific part. It cost me an hour of bottom time. Anyone else have a tool tip that backfired on them?