Just for anyone else who may be wondering on this:
Camera was returned to Nikon last Monday and has been received back today (would have been yesterday, had I been around to take delivery). So all in nine days. Credit where it's due, and all that, Nikon have done the following:
Metering, shutter and exposure accuracy checked - recalibrated if necessary. Image capture, playback and delete
functions checked. X-sync, hot shoe and speedlight function checked. Body depth, body focus, AF accuracy checked
and recalibrated if necessary. Image Sensor, optics, mirrors, and viewfinder cleaned. Firmware version checked
and updated if required.
Repair, replace and adjust printed circuit board.
Check, test and clean equipment
Listed accessories received and returned
Repair includes 6 month Service Warranty
It's a little too early to say if the power will last any longer, but given that I've not been to careful about lens changes - and more importantly, that that is not their responsibility - the sensor clean is a nice added bonus.