david carroll , Nov 27, 2011; 07:34 p.m.
The 50/2 is an excellent lens, but you can pick up good examples in Fleabay for $50. The F mirror lock is supposed to operate as you describe - once you set the MLU switch, you have to shoot a blank frame to lock the mirror up. The F2 rectified this, with an MLU switch that physically moved the mirror up without wasting a frame. That being said, an F with a faulty shutter mech, pinholed curtains and a non-functioning meter = a paperweight or parts. IMO, $20 would be way over the odds. The last F I bought on craigs*list works perfectly and cost me $20. The most I ever paid for an F was $115, for a VGC model with a relatively rare eye-level finder.
All your lenses will work on the F. You'd need the metering prong to operate the metering finder, but since the meter appears not to work, this is moot. Even without the prong, the lenses will attach and give proper aperture operation otherwise.