Hi, I've chipped a tooth on my 13-tooth cog on my IRD freewheel, and it's causing a lot of problems. Skips under load, and worse, throws the chain off on some shifts (if it drops onto the missing tooth, it falls right off).

The freewheel mechanism itself is fine, and the rest of the cogs are too. Can I just replace the 13t cog? How would I find a new one? IRD says not to dissemble to freewheel, so I'm not sure if it's actually serviceable. Out of warranty.

Thanks!