If you can look through the VF, see if it is clear, bright and the rangefinder aligns both vertically and horizontally. Also check the shutter speeds for correctness, stickiness. The shutter speeds are inexpensive to correct, but if the VF is lame in anyway, I would not buy it. The M3 has a great VF, especially for the 5cm lenses; if you love the 50mm focal length, do get a M3 with a fine VF and you will love it for the rest of your film shooting days!