I just bought a film camera. It is a Sears KSX-1000.

[Major Nikon]

14. If it works at all there's a good chance it's accurate

You can check it easily enough. At mid-day on a sunny day just fill the frame with a grey card angled at a 45 degree angle between the camera and the sun with the ISO and shutter speed set to the same value. It should meter within 1/2 stop at f/16, which is about as accurate as you can expect from a camera like that. If you want to calibrate it, simply perform the same test with a camera or meter that you trust, then adjust the ISO setting until the meter zeros and use whatever offset you come up with from that point on. For instance, if a shutter speed of 1/125 zeros the meter at ISO 200, then you'll just need to set each roll of film 2 notches faster on the ISO setting. The error should be linear, but you can always recheck under different lighting conditions to be sure.

Back when I was shooting slides, a couple of the camera bodies I owned preferred to be set one notch from the actual film ISO so I just always knew to put in the offset to get the meter to work correctly.