what to do about grooved drive flanges

[treed2 at u.washington.edu (T. Reed)]

Okay, so the 4K I bought was supposed to come with 100mm flanges but it
turns out it has the stock 90mm flanges. I have 100mm axles so I'll need
to swap the flanges from my old tranny over. No problem.

My only reservation is that I've fought a neverending battle to stop my
drive flange seals from leaking. I'm trying to take steps to change this
such as using a thicker (maybe non-synthetic) tranny oil but I'm
wondering if grooves worn in the sealing surfaces of both drive flanges
are at least partially to blame.

Can anything be done without paying $50 x 2 for new flanges? I remember
someone (Julie?) suggesting emery cloth or something along those lines to
polish them up but I want to make sure before I start removing any
material that the seals will "swell up" the few extra thousandths and not
just leak worse. Anybody know?

-Toby