So I finally got around to really surveying the problem with the rear table not being held in place against the wall with the knob on the cabinet wall (left of fridge).  I got out my bright flashlight and dial vernier and took some measurements of everything using my old knob as a reference point.  The way it works is there is a flap of metal hung wits a tab inside the tube under the top of the cabinet.  The knob goes through a threaded box on the side of that tube.  When the knob is tightened it pushes the flap against the table leg thereby distributing the pressure over a larger area.  Better than just the end of the screw.  Simple enough, but when I screwed my new knob in, it did not contact the flap enough to push it against the table leg. It seems the screw in the replacement knob from GoWesty was just a tad short. I broke out the files and air grinder and shortened the face of the knob that was hitting the screw box on the side of the tube (seen with a flashlight when the knob is removed) so it would go further in  It only took about 3/32 (0.060) and it worked!
So happy to grab the bull by the horns and fix it.
Dave B.the Boston one'87 Westy w/FAS engine