I forgot about the steel fork that came with my first aluminum frame. I was having some headset knocking, couldn't adjust it out, and figured I should let my teammates who worked at the shop look at it (I was 16? at the time). Of course I had a race the next morning so time was tight. One older teammate (and shop guru) said he would reface the frame - he suspected the cups weren't parallel. He started working on the bike by removing the front brake - and the fork blades fell onto the floor.

The steerer tube was not connected to the fork crown!

The only thing keeping the fork on the bike was the front brake bolt. Apparently the fork wasn't brazed properly (duh) and the (steel) crown separated from the (steel) fork legs. Of course I still had this race the next morning. The teammate happened to be a metal guy as well so he took the frame that evening and brazed the fork crown to the steerer. In order to make things look "less suspicious" (this was back in the day when they inspected bikes before a race), he spray painted the crown and the top of the legs in the morning (a similar red to the original color). I wrapped the seam with some tape that matched my kit to hide the seam and to try and distract any inspectors from noticing the mismatched paint. The paint was still sticky when I went for inspection but no one said anything. I raced that frame/fork for maybe another two years. I wrecked the frame but I believe the fork is still in service.