truck won't turn over?

[pyroimpala]

Just picked up a '62 C10, inline 6, 3 on the column.

Guy we got it from said he was driving it up until a few weeks ago when the starter just quit on him. Turn the key and the starter clicks once but won't turn the motor over.

Got it home, took the starter off and checked it at the part store and it passed.

Also was able to turn the crank pulley and could see the flywheel turning so motor isn't locked up.

Just wondering what I need to be looking for now? Bad ground or what?

Weird it would just quit on him if the starter is still good.

Thanks,
--Marcus