You need a proper set of lock ring pliers. If you're using the kind with the little projections on the tip, I feel your pain. I tried them and almost lost my mind, as well as a couple of fingers. One of these should do the trick:
Craftsman 47386 or 00947386000
Occasionally you'll have to de-burr the edge of the groove and/or the edge of the ring with a file.
Last edited by jimfulco; 05-26-2006 at 11:19 PM.