I recently purchased a used Craftsman Radial Arms saw. This is a new tool for me in great condition, but I am not 100% familiar with it. The guy I bought it from fired it up when I picked up and everything was working fine. Once I got it home, I can't get the carriage to move. It is locked in position to the rear. I have turned the carriage locking knob to release the carriage but its firmly stuck in its position. Not sure what I am missing, any help would be appreciated!