David 2 - advancing the warp

You lift up the leaver with your right hand and advance the cloth beam with your left. 

If the warp beam does not come loose, this could be caused by the brake pawl being on the ratchet wheel of the warp beam. The string brake has taken over this function and so the toggle on the back ratchet must be disengaged .

If the belt brake is set too tight, this can also be the cause of the warp beam not letting go. Loosen the knurled nut at the belt slightly. The boom lever should be approximately horizontal.