All Lever FP1 Power Feed Shear Pin Manufacture

Hi everyone. I have a late 50's FP1 with levers that the power feeds have stopped working. I was lowering the table using the power feed when it stopped moving. I have noticed the Z axis sometimes locks by itself when I lower the table towards the floor. This has happened a couple of times now but have not been able to figure out why. I believe it is the Z lock the is preventing it from moving but can not be sure. Both the X and Z have stopped working and I believe the power drive shear pin is sheared. I only have the top side of the shear pin so I do not know the dimensions needed to make another.
I was wondering if I could make my own shear pin and if so what are the dimensions? Should I follow a specific procedure when replacing the shear pin?