In any case, you'll need to remove the door glass guide from the door, so remove the motor/regulator as well. You can test the motor/regulator out of the door to see if it operates smoothly. If it doesn't, you'll need a replacement.
The other culprit is the nylon bushes on the door glass guide assembly. Here's what the DGG assembly looks like removed from the door.
The bushes are on the bit that holds the glass, which slides along the curved shaft. Here's a closer shot of the bushes - they're the white nylon things.
Both of these bushes wear. The upper bush wears on the inside AND the outside, which means that not only is there too much play between the bush and the shaft, but the bush also moves around within the assembly. The lower bush generally only wears on the inside. The stupid thing is that the bushes aren't replaceable items :x - the entire assembly is treated as a part (apparently, you can still get the driver's side assembly from Mitsubishi, but they're not cheap and have to come from Japan). The top end of the shaft appears to be squashed (where the mounting nut is welded) after the bush is placed, so although you get the bush off by breaking it, getting a new one on without wrecking the shaft could be tricky. The lower one is not held in by bolts - the other side of the bolt-looking things is splayed like a rivet. Potentially, you could take these off and replace them with bolts if you could find a suitable bush.
I set myself the task of getting the door glass to operate smoothly using materials I already had (ie, without spending any money).
All that's really necessary is to take up the slack in lateral movement of the bushes. I decided to cut up some plastic sheeting into strips to pack the bushes. I used some plastic sheet I got from Clark Rubber that I previously used to cover the rear carpet area of my wife's car. This is nice and hard wearing, so should last a while.
Important! I needed to make sure that there wouldn't be premature wear of the plastic sheeting (in particular by nicks or burrs on the shaft), so I cleaned and sanded the shaft with 600 and 1200 wet & dry so I'd be sure it was pretty bloody smooth.
Here you can see the how I used the plastic strips to pack each side of the upper bush:
The lower bush was a bit more worn, so I used two strips on each side:
Then I folded over the strips and secured them with a cable tie:
This is after doing both sides and trimming the cable tie and plastic:
This is the upper bush after doing the same. You'll notice that I've used two cable ties here. The inner ones secure the plastic packing and also stops the bush from moving in it's mounting area. The outer ties keep the inner ones in place :)
Finally, I greased the entire shaft and bushes really well, then worked the shaft back and forth to spread the grease properly. Then greased again. And again. And then a bit more :) Gotta be a little bit careful, because with the plastic packing, there'll be a tendency for the grease to be squeezed out.
It's now back in the door and working really smoothly - now I just have to see how long it'll last :). If it doesn't last for very long, I won't be saying anything
