Email Citizen Japan or your local Citizen subsidiary (e.g., Citizen Watch America) with a photo of the case back. Provide the string GN-4W-S-12G. Their archivists can cross-reference production codes.
A: You set the time 12 hours off. Pull the crown to Position 2 and advance the time 12 hours forward. citizen eco drive gn-4w-s-12g manual
The most common "issue" users have is a watch that stops or starts ticking in 2-second intervals (the low charge warning). The manual explains this, but here is the practical fix: Email Citizen Japan or your local Citizen subsidiary (e