I'm such a cheapskate. I bought an "as-is" F3. It actually works, but the meter is a little off, and the light in the finder doesn't work.
I found these instructions via DuckDuckGo, but didn't think it would work for me because it didn't feel like my button depressed at all. I tried it anyway and, surprise surprise, it worked! It's really easy, if you want to give it a try:
That illuminator button is not implemented very convincingly, but I’ve seen a couple of instances where owners didn’t realize that power needs to be turned on, and the shutter button needs to be half depressed just before pressing the fiddly little button.
My epiphany was after using my F3 for 5 years I finally read the damn instructions, the light meter didn't work until you had advanced to frame 1. Something that was eliminated with the Nikon F3P. It's a beautiful camera, but definitely rather effeminate after the F and F2. MHO, don't bother to argue I'm going to Netflix.