Notwithstanding the caution by CeeVee, I did the following. I thoroughly washed the shades in warm soapy water and allowed them to dry overnight. I then sprayed a Q-tip, using a plastic tube to direct the spray, with a small amount silicone lubricant (for my retractable door screens) and used the Q-tip to gently wipe the contact areas of the shade. It improved things quite a bit.
One of the reasons for this frustration occurred a couple of weeks ago when I was at a bird watching location and I needed a quick lens change. I'm a bit of a nut about lens shades and almost never shoot without one. Putting on the shade for the 50-140, or rather struggling with it, almost made me miss my shot. Of course I could have shot without the shade, but... OCD rules.