I'd had some trouble with the lensboard staying properly in place on my beseler cb7 enlarger. One clip was missing, so I tried to substitute my own little retainer strip in. Still the lensboard had some movement.
So I got out my electrician pliers and a coat hanger, and made two nice spring loaded custom clips to hold the lensboard in tight. There are holes seemingly built-in for the purpose on the sides! These coat hanger clips stay in nice and tight, and can snap out if you tug on the side vertical portion with a needlenose plier.