If you are still playing-
This is what I would try if you can't hold the flats on the cam.
Presuming you have a 1/2 socket set.
Fit as big of a socket as you can through the pulley and into the core plug hole.
Fit as many extensions as you have into socket.
Use your breaker bar on the bolt and hold the extensions straight while you undo it.
Put the head on the floor and get someone to hold it. Don't want to break your table
Don't need plus gas.