Last week I noticed my RH passenger window wasn't working. Heard it click (so current was going there!) but not working up or down. Out came the trusty Bentley's and I removed all the interior stuff. Note, buy a new plastic cover for the screw under door handle - it's a bugger to get off (I ended up using a knife). Anyway, I loosened the adjusting nut for the window mechanism, worked it up and down and, TADA, it was fixed!
Just a head's up to anyone that suffers this mysterious malady....