I found what I think was a good deal -- five pin lock cornies for $100. The seller had found them in his garage; apparently his dad had bought them for brewing at one point, but never actually used them.
I quickly tested all by pressing down the gas-in pin with a chopstick -- three were already holding pressure, and two were not. I was going to attempt a science-experimenty test with baking soda and vinegar (thanks, MC!) but the owner just said "let's blow some air in them with my compressor!" Well, that did show that the other two kind of leaked a bit, but I'm willing to write that up to the fact that they're all filthy, and there was likely gunge in the seal and/or the lids weren't properly seated.
Two still have original Coke tags on them, the rest do not. Two have what appear to be intact PRVs, one lid has no PRV at all (weird), and two have what look to be broken
PRVs. I'm attached photos below.
Short of obviously stripping these down and oxicleaning the heck out of them, does anyone have input as to their condition. Are the "broken" PRVs actually broken? Can they be used as is? Can they be replaced? I'm an absolute newbie at this -- I've never used a keg before in my life. I don't even have any other parts yet, including CO2!
Thanks in advance for your helps, ladies and gents.
Tops of all five kegs:
A closeup of a "broken" PRV: