Brand new wheel for the start of a 400km ride, and 60 km in, the back wheel had developed a wobble. Stopped at the RR crossing and all the spokes had backed off, with one of the nipples completely unscrewed and floating inside the rim. Now having never built a wheel this was an interesting dilemma. Locating the appropriate small diameter weed to insert the nipple and twist it back on the spoke was challenging. Then the frame became the truing stand while a coal train passed by.

Lesson learned, never attempt procedure on a pea gravel surface, very hard to find the nipple when you drop it.