Also, when you say...

Quote Originally Posted by tkamiya View Post

Before you try to move it, make sure it's locked up. If you look lower right of the beam, you will see a small plastic locking "thing" with a thumb screw on it. Otherwise, the carriage will slide up or down while trying to move the whole thing.
does the knob resemble the lock nut on my B-22. I attached an image below. Thanks.