Dredging up more old threads.

I now have four, older hand-held infrared sensors. I had thought to start breaking them down, only to find that they are all held together by dozens of really, really small hex bolts, in my case quite rusted. Before I spend a lot of time with a precision bit and WD-40, is there really anything in them worth recovering? I was able to get the scanner/lens/shiny thing off the front of one and see what looked like loaded (but low-grade) board inside. I figure most of their weight is from the housing but are there valuable components, too? Can they be sold as replacement parts or has the technology changed too much?

Respecting this thread's history, I am not going to refine anything I find.