Window will not roll up completely

My manual right-rear window (95 Sedan) will not roll up all the way, leaving 1" gap from the top. It was working great for 15 years:(
Any advice?
Window rolls down smoothly and rolls up smoothly no hop, then just stops dead 1 inch from the top.

It could be binding in the vertical guide channels. Try spraying them with silicone to see if it improves. My windows used to hop whenever I put them up, but this solved it as a temporary fix.