Do you mean the chain is skipping on the first two cogs? You probably need to replace the chain and the whole set of cogs. The outer cog probably needs to be unscrewed and the others slip off.
If it's an older uniglide hub, you either have to get new old-style cogs with the right tabs to fit the grooves on it, or you may have to grind off the one wide tab on the new cogs to make them fit. That's what I did recently.
If you can't find a screw-on 13 tooth outer cog, you can try flipping it the other way around and screw it back on and see if that works and doesn't skip. I did that and it worked.
Or you can get a new wheel.
Last edited by cooker; 06-08-08 at 07:45 PM.