I've come upon mention of people stating that you can send dim sights in to XS and they will install fresh tritium vials for a fee considerably cheaper than a new set. I contacted XS in regard to this service. Here is their response;

Yeah, whoever said that was totally wrong.

The way they are sealed into the sight bodies, getting then lamps out, refinishing the sight bodies because the removal process ruins the finish, then putting new lamps the cost would be more than a new set.

We have never offered such a service.

.......it was sent from Bo at XS tech support. Seems pretty cut and dry to me. I just wanted to clear this up if anyone else heard that rumor. Brian