Hi just bought a used Craftsman circular saw.

Model: 315.108400
11AMP
7.25 inch blade type.


Anyway, trying to remove the old blade from the saw, and so I am using that
wrench
socket thing that came with the saw to try and unbolt that bolt and the
whole blade just keeps spining.

Is there a trick to locking that blade down so you can use the wrench to
loosen the nut and remove the old blade?

Or did I just bought myself an unusable saw?