I rebuilt the headset on my Shogun 650B conversion at the time that I built up the bike. It's the alloy version of the Tange Levin, and it was smooth as silk when I built up the bike. After clocking in about about 400-500 miles total, with about 50-75 of those being fire trails (some quite rough), I've noticed that my headset is indexing in the center position. It's quite noticeable. Once off-center, it's smooth. Backing off the upper race reduces it, but if I back off enough to eliminate it completely, slight play can be felt. When rebuilding the headset, I kept the original ball retainers but swapped in new grade 25 balls, and also had the head tube professionally faced. Would swapping out the retainers for loose balls cure it? Or does this generally indicate the cups are toast?

I have a theory behind why this happened after so few miles, but I'll wait to hear what others say first.