I received a PM regarding questions on buying older V-series Hasselblads, so I thought I'd share the answers here with everyone as well.
Older Hasselblads such as the 500C/M are good buys because they're very rugged in built and they continue to accept the latest V-series lenses and accessories. But for someone new to the system, they may want to find out how to purchase a good copy of the camera and avoid problems. So I've listed some of the issues you may find with the older V-series cameras:
1) Light leak (very common)
Light leaks are very common on older Hasselblad cameras, but the leak occurs at the film magazine and not the cameras. The foam and felt lining in the magazine wears out due to age or use, and they can be replaced at the authorized agent or camera repair shops.
2) Sticky mirror (less common)
Sometimes the foam in the mirror box disintegrates with age and becomes a sticky goo, so the mirror may get sticky and not return to the down position smoothly. Send it to the agent or repair shops to replace the foam and clean up the camera and you're good to go.
3) Sticky shutter speeds (common)
With any old mechanical cameras, sometimes the shutter speeds are inaccurate due to dirty gears or insufficient lubrication. This is especially true for the slower shutter speeds. It's not a big issue... send it into the workshop and they'll get it up to specs again.
4) Sticky or oily aperture blades (less common)
Look into the lens and stop down the aperture - do you see oil on the blades, or do the blades open and close smoothly? Old lenses (or used in hot conditions) may suffer from aperture blade issues. Nothing major that the workshops can't clean up though.
5) Jammed lenses (user fault!)
Hasselblads are very nicely machined cameras, and everything should fit nicely and smoothly. The problem happens when it lands in the hands of ham-fisted photographers who use excessive force the wrong way. Hasselblad lenses MUST be cocked before mounting/dismounting, and some ignorant users forcibly mount or dismount the lenses when they are uncocked. Inevitably, the lens and camera locks up permanently. It's easy to solve though - remove the magazine, open up the rear baffles and mirror up (use the mirror up button), and CAREFULLY use a small phillips head screwdriver to **** the shutter through the back of the camera using the "screw" at the bottom of the mirror box. Fortunately, Hasselblads are built tough so such things won't frazzle them at all.
In case you feel that old Hasselblads are difficult to use or maintain after reading all these, don't be mislead by the bad news. The problem lies in the fact that many disused Hasselblads are not maintained properly, and like most of the mechanical stuff out there, once you send them in for proper servicing once, and continue to use (not abuse) them, they will continue to work for a very long time without any problems!