This is NOT about lock-up of the B1.
The problem is with the little silver thumbscrew with radial grooves inside the main black lock-down knob. That is the one with which you can set the minimum friction of the ball-head when you loosen the black lock-down knob.
The problem is, that the friction preset does not work any more. Whatever setting I put the little screw, from about 1.5 mm protruding outside the main knob, to all the way, about 1.5 mm recessed from the main surface, if I un-lock the main knob, the head is all floppy.
Is there some procedure I can do, or is that a question for repair? Is this a known problem of the B1? I also have a Linhof Profi II for small format, which has two wheels, one for friction preset, one for actual lockdown. Although the Linhof is older, and possibly used more, no problem with the friction preset.
Thanks for any insights.