www.mcmaszter.com is a great source for knobs and all the other hardware items that modern local hardware stores no longer carrry.



The "Sterling " type holders that your B&J (and other 11 X 14 cameras) have the locking bead near the end of the holder. Graphic type holders have it right near the image opening.



It's interesting that B&J advertised that the multiple knob arrangement gave the photographer the option of on-center or off-center back tilt.