At around 08:00 this morning I witnessed a reset of the WS3600 base station. There was a beep, the display cleared, then all LCD items turned on and then the backlight came on. Finally, after a short while, the display went back to normal and a minute or two later data was being received from the transmitter again.
Of course, if there's no wind at all, the vane won't move, but in that case I don't actually plot a point on the graph — I only plot a direction if there's an associated wind speed.
I suppose it's possible that for all that time the wind vane managed to record exactly the same direction but I've never seen it do this before in all the time I've been running the station. Given how much rain, hail and snow we've had over the last few days I'm wondering if the vane actually froze in place. One bit of evidence that makes me think this might be the case is the fact that the direction settled back into its normal plot (varying around a general direction) at around the same time as the Sun would have started to warm it up (around 07:00 this morning).