Hi there. I recently received a nice old Seamaster, with a CAL 266 movement.

It was sold as working, and I trust the seller, however on arrival I have an issue.

I can set the time correctly, and smoothly, however I can not wind the watch.

When turning the crown anti clockwise, it clicks.

When I turn it clockwise, it has resistance and will not turn.

With the caseback off, gears 1 and 2 (as per below) turn very slightly, and the (cam?) in 3 will turn to the point highlighted with the arrow, and that is when there is resistance.

Any ideas what is happening here? Appreciate any technical insight

 

Is the watch running? If so, it's fully wound - no problem, let it run and wind down.
If the watch is not running then it needs a service and possibly parts.
Wining anti clockwise does nothing, it's not an indication of anything.

 

The watch was sold as running, however I can not wind it, nor will it run as a result. It feels as if something is resisting in the winding mechanism.

 

Are you able to return it?

 

Well it sounds like it may be fully wound.
Here's something to try. With the back off, put a little pressure on the crown (clockwise), then use a toothpick or similar to move the click (3 on your photo) so that it's no longer engaging with the teeth of the wheel on top of the mainspring. Then let the crown slip anticlockwise through your fingers (applying a little pressure so it doesn't run too quickly).
This is letting the mainspring wind down.
When it's finished you should be able to wind the crown again until it's fully wound.
If it's still not running then there's definitely a problem that extends beyond the ability to wind the watch. Request a refund and return the watch, or decide to keep it.

 

Likely fully wound and not running. It needs a service.

 

I advise against doing this yourself - if something slips you can easily cause damage to parts...