We have double pane windows. I noticed that one of the windows got
stuck. We didn't paint them or anything. They came with the house and
are 4 years old. This window is one of the frequently opened windows in
the house. During this summer since the A/C was on, we didn't open it
for 3 months or so. When the weather got better, we tried to open it
and it was very hard to open and even harder to close.

We never lubricated the window since we bought the house. Should we
lubricate the window once in a while? What kind of lube should we use
for this? Will this fix the problem?

Thanks.