faulty electric window

I have a 1991 9000iS, in Hampshire, UK, and found today that the driver's side electric window would not open. It does sound as if it is trying to close further when I press the 'close' side of the button. The fuse is OK, and the passenger side window and all others work. I took the switch panel out, but could not see from the connections underneath how I could test it. Does anyone have any suggestions for locating the fault, before I start taking the door apart? Robin Milford