Hi Tony,
I am now 9+ years with my Davis VP2 and have had no issue, no replacements of any kind, never taken it down or apart, it just keeps on working (fingers crossed) and is in 30°C + and - conditions. I've just replaced the ISS battery which has been in for about 7 years and both the first time and now I have replaced it just because, and winter was coming.
Enjoy,
Paul