Cassette/hub noise problem
 

My Campy (10 speed) cassette or free hub is making a weird noise only while on one cog. The noise sounds like a hub pawl grating noise that modulates but not in synchrony with the crank rpm or speed. The cog is tight.

The cog is mid range (third from highest). All other cog positions run fine with no noise. I'm running Mavic Ksyriums on a cross bike w/ road components.

Any ideas?? Thanks for your help!!

If they're older Ksyriums, you might want to remove your cassette and spin the freehub body by hand, feeling for resistance. Even removing the freehub body shell from the hub to inspect it wouldn't be a bad idea. I remember older Mavic wheels having problems with the hub body cracking where the pawls seated. This would cause it to rub against the inside of the freehub body shell, and sometimes make it incredibly difficult to remove. Take advantage of the warranty if this is the case and if it applies.