Just wanted to relay the utility of this cheap-o USB borescope. I bought one on Amazon for $15 - and simultaneously I bought a more expensive one to compare. I ended up returning the more expensive one (with a goose neck, etc), in favor of the cheap-o.
It was helpful to look for loose connections when I was troubleshooting a wiring short far behind the panel.
It takes pretty good pictures of valves. To do this I bend it back on itself and duct taped it to a stiff wire.
Good stuff
-B
https://www.amazon.com/gp/product/B016KUGVJC/ref=oh_aui_search_detailpage?ie=UTF8&psc=1