I recently received my Ref. 371323 back from a full service in Schaffhausen, and like some have requested, was fortunately able to retain my original tritium hands and dial. The case was well worn, and the caseback was damaged, so I did have it refinished back to factory specs - it looks fantastic and is functioning beautifully!
I had originally wanted to have it serviced 6 or so years ago and talked to a service executive with IWC about having it done (one of the advantages of being invited to a collectors' meeting). I mentioned that I was a bit concerned, because I did not want my dial or hands replaced, and I knew that tritium could sometimes be an issue, especially if it is degrading. He asked me if the watch was running fine, and I said that it was. I told him that the watch had not been serviced since it was purchased new in 1996, and I was worried about the oils drying up. He explained that as long as it was keeping good time and functioning correctly, there was no need for service. And I was told that when I were to finally have it serviced by IWC, they would replace any worn parts as part of the service, and those parts would not incur any addional costs. I was further advised that running a movement of that age was not a risk. The Valjoux 7750 base caliber is robust, parts are commonplace and relatively inexpensive, so I was reassured and wore it until I finally did have an issue. My crown became diffilut to engage the 2nd and 3rd psotion, and the stem needed to be replaced.
Fortunately, the Wizzards of Schaffhausen were up to the task and returned this beauty to its former glory. Full movement service, case/clasp refinishing, crown and stem repair:
