THE RETAINING PIN FOR THE BRAKE CONTROL KNOB HAS BEEN MISALIGNED (OFF THE CENTER LINE OF THE VALVE PLUNGER HOLE). THIS CAUSES THE KNOB TO BE OVERSTRESSED AT THE RETAINING PIN HOLE AREA CAUSING IT TO SEPARATE FROM THE VALVE.
FixTHE HOLES WILL BE RETOOLED TO PROVIDE CORRECT ALIGNMENT AND PLASTIC KNOBS WILL BE REPLACED BY KNOBS OF STRONGER MATERIAL HAVING METAL REINFORCEMENTS.