For a few years many of the Mavic rims' plug, which is used to align the two ends of the rim at the seam, would work loose over time. There was no issue with the rim's integrity as the spoke tension pulls the two ends of the rim together. But with each rotation of the wheel this plug would shift slightly causing a click/clack that was very annoying if it was on your bike, or the one next to you. Some would try to drip glues into the rim, others tried tiny sheet metal screws to secure the plug. Most just tried to ignore it. Andy.