Originally Posted by Irvin
I would try putting a little toothpaste on the inside of my clamp and putting it on the bar down at the end.
Ah, the MINTY approach!
Alcohol always did the trick for me. Remove the clamp to access the full length of the glide bar and rub away. I would also wrap a cloth or paper towel around my pinkie and clean the 'bar clamping' portion of the clamp base.
Just for grins, you might switch the clamps from bar to bar and see if that makes a difference OR gives you some feedback as to the binding culprit.
If your vehicle headlight lenses are severely oxidized, you might try the toothpaste trick on them as well...good for polishing/cleaning...then apply some sealer for protection.
Duct tape, WD40 and toothpaste....what more could you need!