Typically the failure is not in the actual meter, but in either the communications card, or the processing card (if separate). These were both new components added to the meter to make a "dumb" meter a "smart meter". In most cases is it a heat related failure of a chip or soldier joint. They typically discovered in the annual batch sampling or from having to replace the meter for non-communications or data that is communicated but does not make sense. Another failure is in pushing firmware to the meter and having the meter become non-responsive.
In some meters, if it is firmware related you can push new firmware locally with the optical port. Some manufacturers have developed low power RF devices that can push firmware to the meter locally. This can typically solve 15% or so of the issues.
In other hardware related issue, it may be batch related, and if it is, the problem can be solved by replacing the batch - if it is on the cards, the base meter is fine and can be brouhgt into the meter shop and the card(s) replaced. In the few cases where it is meter related or latching relay related (disconnect) the whole meter will need to be replaced - make sure you do a root cause analysis and keep track of which batch the meters were out of. This will help identify the batch issues and the extent of the problem.
The IRS has set the lifetime of AMI at 15 years, and if your system is approaching that age (or past it) you should be seriously thinking about a next generation meter. That next generation meter should have far more bandwidth, less latency, more firmware space and if a HAN - then it should be a WIFI type HAN and have a firewall to go with the HAN.
I wil be happy to take a call if you think that is useful - no sales pitch.