It sounds as if the weather strip is binding or hinges are starting to sag.
Vinyl window won t close all the way.
Despite their durability here are some potential problems that require vinyl window repair.
Window is sticking unscrew the hinge and remove the window that sticks.
Windows that won t open and close properly.
If you look around the window frame and the sash check to make.
If your window won t open or shut try using these steps to remedy the situation.
It might need to be adjusted diane.
Or there is some expansion to the window sash or frame.
That s probably because they re out of square.
The easiest problem to rectify is a dirty window track which you can clean with towels and brushes.
Add some oil to the hinges to see if that helps.
This problem is usually due to hinges that are loose or need lubricating.
The windows won t slide down far enough to latch.
And if they re not locking then something is swollen or out of square.
2 if your window is hard to close and you see there is dirt or debris in the window sliding track clean it out with a canister vacuum and or wipe away any of the objects making it hard for the window to close properly.
So you really need to push them push the bottom window down and the top window up enough where you can lock them together.
Make sure the hinges are tight and secure.
Using a small hand held plane shave off a few millimetres of the edge that is sticking.