Davis recommends replacing the motor and batteries every two to 3 years. I purchased the 24 hr fars from scaled instruments in june 2013, that would be about right, just shy of 2 years. and of course there could be a chunk of ice in there as well. So.. depends on whether I want to take the station down and bring it inside or. wait until spring when it is warm, and do it outside.
The only pain in the hind quarters would be fishing the wind sensor wire out of the ISS. I wish they made that portal a tad bigger and more slack. However... I could hold off until April . I doubt that the FARS difference in winter would be all that much of a difference. In the hot weather, I had 1.3 degrees less than a passive sensor.