In the early hours of Wednesday 1 October 2014 the transmitter unit on the N96GY weather station stopped transmitting data.
This was a surprise because new batteries had been installed less than three weeks previously. Nevertheless, a new set of batteries was installed. Unfortunately this did not solve the problem.
When the new set of batteries was installed the red transmission LED inside the tranmitter unit came on and stayed on. This indicates a problem with the transmitter, and if it persists across repeated battery pulls (it did) then the received wisdom on several internet forums appears to be that the unit has failed for some reason. Normal behaviour is for the red LED to illuminate only while the transmitter is sending information to the USB display unit.
Thankfully, spare parts for the weather station are now available so it looks like I do not have to replace the entire unit, just swap out the offending transmitter. I am currently awaiting the arrival of the replacement part (N80NF at Maplin) which I expect to arrive mid-week. In the meantime I will post manual weather summaries as I get the chance!