Megado - electronic / dobby - Dobby knife bar dropping shafts / screw heads

Check that your dobby is physically well connected, nuts are tight, dobby is as close to the loom as it can be / should be.

Your dobby's solenoids fire when the pattern asks for  that harness to be raised.    The solenoid pushes forward the looms "dobby hook".   On the inside of the loom, side of the dobby hook, the screw head is pushed forward.    When you push the treadle down, the knife bar comes down and pulls downward all screw heads that have been pushed forward.  The screw heads are only partially screwed into the dobby hook, so that the knife bar falls into the gulley between the knife bar and the extreme outer edge of the screw head.

This article talks about a solution for the situation where these screw heads fall off the knife bar.  

If the solenoids are firing well and fully extended, and the dobby is fastened to the loom well, try unscrewing the screw heads that are getting dropped. This way they will extend out a little further. Don’t unscrew too far as they will then hit the knife bar while at rest.  If any screw head outer edge just rests on top of the knife bar, then that screw head is not unscrewed far enough.