The parts to repair my Monocog came today, and consisted of a new top bearing race/cap and centering sleeve. I installed the new parts and the headset is perfect now. I inspected the old parts, and it seems that the old race, where it fits beneath the top cover, is a bit loose and could have caused the clunk. Even if the centering sleeve weld everything in place as it should, the race was still loose underneath the cap. BTW, what brand of headset came on your Raleigh? It may be the same as the Cane Creek/ VP that came on the Monocog.