Hi
Cinq or panda..?
Being winders.. do you mean a handle..??
Well 3 possibilities really :
Out of square and jamming
Damaged mechanism
Obstruction.. bottoming out
Weird how they both do it...
One idea.. rear windows have reduced travel.. as the wheel arches mean the track length is shorter..
Possibility of bodgery..?
Idea.
With an assistant aiding you..
Stand on end of door one palm either side of window glass
Support the weight of the glass as assistant winds up and down.. does it move further.. (sticky mechanism)
Quite possible that is the range most windows see in everyday use... ventilation
Modern puntos have rear windows that seize up if not used..
Let us know what you find
Charlie