door panels easy, unscrew the arm rest, unscrew the opener & slide foward, you'll then need to unclip the bar off the back of it(try remember how you did it, coz it can be a mission to refit), the hardest part, the window winder, a long thin screwdriver in behind it to pull the clip out, its a U shape, if youre unsure, try look at one thats already off, else you probably wont be able to figure it, i lay the screwdriver flat under the winder hard against the panel & wind, the clip should catch the head of the s/driver and release, then slide the winder off. pull the door panel out from the bottom, & you'll here all the clips pop out, then slide the panel up & off the door, easy as pie.
check your 3 bolts holding the regulator(the splined part your winder goes onto) make sure theyre tight, as ther is a bit of adjustment in these, you may need to work out where it works best & tighten. there should also be a bolt head sticking out on the latch side of the door jam, this adjusts your window chanel(that the glass slides into) check that to make sure its not out of shape.
i had a similar problem, & it was simply loose bolts on the regulator,
good luck.