In article ,
joe@azurite.demon.co.uk says..(post asking how to select used body del.)

It often happens that people "wear" their camera(s), more for show
than to take pictures, and they can look terrible, yet have good
user life left in them. Operate the film advance and shutter release
a few times to see if all sounds and feels normal (someone familiar
with the body in question would be helpful here). If the camera
exterior is acceptable, and everything of importance to you works correctly, look inside for wear marks. With low use, you will see
few marks in the matte black paint on the inside of the door, you
will not see any marks or wear where the cassette fits and in the
center of the right edge of the shutter opening (places that will
show paint wear with considerable use), and you may see barely
visible parallel hairlines in the pressure plate surface when it
is held so that light reflects from it (if they are non-existent
or VERY hard to see, guess that less than 50 rolls have been through;
if fairly easy to see, maybe 100 rolls or so; if obvious and easily
seen lines exist, especially if bare metal is visible, pass up the camera). If there is no oil on the shutter blades either wound or released, put the shutter at the top speed, and release it a few
times while looking through the body (with no lens on) at a light
area to see if it opens completely on both sides of the frame (top
and bottom for FE type shutter - these shutter checks are not very
practical with newer bodies unless you know how to cheat the door
key so the camera will operate as if it had film in it). Try the
same thing at the top synch. speed with a flash on the camera to
see if the synch. is correct, and the shutter is fully open for the flash. If the camera passes the checks above, buy it with a return guarantee, and continue checking at home. Check the meter for
"bobbling" or irregularities when the aperture and shutter speed
rings are turned. Check the meter at various light levels against a known and trusted meter (if the new meter agrees with the known
meter except for a constant error [like 1/3 stop], just apply that change to the ASA or compensation setting on the new camera, and
don't worry about it). (For ways to check viewfinder focus;
parallelism of screen, mount, and film; and framing [centering and rotation], watch for my article on lens checking, coming soon, I hope!)
Hope this helps.