I had a sticking Fly Screen in the overcab and one of the blackout blinds started sticking a bit whilst away at Easter. I purchased a small can of Holts Silicone Spray Professional from a motorfactors (for another task) and carefully sprayed it into the top and bottom corners of each blind (blind closed, fly screen extended). Both the Fly Screen and Black Out Blind have quite literally sprung back into life. Not sure if cheaper silicon sprays for tyres/trim are as good but worth attempting if you have this problem.