Where is it wobbling? They will never be completely stable as you need to allow room to move at the joints, thus wiggle room. The original clamps do work but need to be continually adjusted. If it’s the main mount on the bench, longer screws will help or change to nuts/ bolts with a backing plate. If it’s the sliding part of that mount, good luck. I added a bit of electrical tape and that helped but soon needed to be replaced. Mine, I removed and replaced with tv tables.