Reply by Mickey Cassiba

The locking knob would be a wing shaped handle in the center of the elevating Handwheel(also the tilt handwheel). Inside the hollow shaft that the knob screws into are two steel balls that press against the inside if the shaft locking the mechanism in place. The servicenet site is a little wonky, or I’d post a screenshot of the detail. What model number have you got?
Love your signature BTW ;P

-- One of these hammers oughta fix that...