Lately, my AT4010-50E Eco-Drive has not been syncing with WWVB at night. I've verified the signal strength of the transmission using my ham radio and tried various placements in windows, etc. This watch usually only misses a nighttime sync once every few weeks from my dresser top. Also, after attempting an on-demand reception, it would fail and the second hand would begin ticking in 2 second intervals, indicating low battery, though the battery would test full charge at other times. Charging on a sunny windowsill for days made no difference.
I sent the watch to Citizen in California for warranty repair (just under 5 years old) and they sent it back via UPS ground stating they received the watch "not zero reset properly" and that they recharged the watch and reset it. After a 3 week turnaround (including coast to coast UPS ground from their end) it came today and is no different than when I sent it to them. I called their service center and the friendly rep said the battery should not behave that way. They sent a ground UPS label via email for return to their service department in California. I'm not convinced this is merely a battery issue or a symptom of a larger problem.
I've read nothing but good reviews of Citizen repair. This was not one of their success stories. Hopefully when my watch is returned to me this time, I'll have a good report.