Can you feel play in the glass relative to the passenger side glass? I would first suspect a dirty switch before suspecting binding glass. I have a '98 model S40 (was not available in the US) and by now all the windows go up at different speeds. Or it might be as easy as spraying silicone spray on the edge of the glass and raising/lowering it a few times before wiping off the excess.

As for opening the door panel, it is a bit of work. There are screws hidden in funny places, but it doable. I recommend getting a manual, even Haynes will do. It shows you where everything is. My manual will be of limited use, being only for the models up to 1999. When you get the panel off, everything inside is covered with a plastic film which is glued on very well. You will break the film. In the old days the film was glued only at the top and the excess draped inside the door frame, but modern cars have it glued all around.

The parts that are hard to open and do get damaged, are things like the clips for the door lock mechanism which you will probably not have to remove. With getting the cover off the damage should be no more than possible scratches on the screw covers.