Dan,
Ha, of course I opened it and I tend to think I'm fairly technical, so first I thought a spider might have taken up residence, and indeed there was a very tiny one living in there, but not the problem. So, not knowing about hygroscopic coatings, I decided I'd just "clean" it a bit with alcohol - biggie mistake, it apparently dissolves hygroscopic material and the sensor promptly went to 10% and that was the end of the story, so lesson learned, but no great loss.
I'm in a bit of a quandary regarding the weather station, it does have a "following" and so I feel a responsibility to the community and of course gratitude. I rent this place and I'll be leaving in a year, so there is no telling where the new casa will be or what its configuration will be. So, investing in more OS gear is one option, or limping a bit until next year and then deciding on a Davis wired, or wireless or? - will be the challenge.
I'd love to have the resources (see $$$) to buy three or four professional stations and place them at different points along the N shore and S as well. As we all know, "weather" can often be very localized and so when I get rain here someone 15 miles away carps about none. And temps vary considerably due to lake/mountains/thermal mass etc. and so it would be fun to have several, but it is what it is and Max the WeatherCat and I do the best we can with what we have.