I had them and loved them but when the humidity got up there there was no opening or closing the dang things. And no amt. of spray on lubricant helped. The wood behind the vinyl is swelled. Manufacture suggested using a blow dryer and it did the trick.

My husband said to spray Endust on a rag and wipe the window jam on both sides. Let it dry and slide the window up. Use as needed.

W-D 40 always works for me. I use it for several things when they get sticky or harder to use. It is great stuff