You could check with STS UK to see if they can fix it : http://www.swisstimeservices.co.uk/ - they may have spare modules... Incidentally I finally saw one the other day and was struck by how "tiny" it is, very much dates it to the very 80s.
May be an easy fix if the watch is still running and keeping time. I think the pins are misaligned on the lcd crystal. If you remove the four screws on the top and then loosen the holding clamps, you can slide the lcd crystal enough to realign the pins. Voila! Be Careful.