Cleaning the slot that the window goes up into (technical term you understand) with a bit of white grease or something similar on a tissue or rag should resolve the problem. Had the same problem on mine and have to do this a couple of times a year.

 

I suspect that one of the two glass clamps that hold the glass in place has become loose or broke.

Basically there are two clamps that grip the window glass that are mounted to a pair of vertical runners inside the door.

You will need to take the door card off (very easy just take your time) and then you will be faced with this :

o
As you can see I have shown two red arrows which point to two rubber access plugs, take these off and then this will allow you to see the two glass clamps when the window is wound about half way down.

There is an M6 (I think) hex set bolt on the clamps which is used to tighten the clamp up on to the glass. There should also be some black rubber shims/grips that sit between the metal part of the clamp (think vice jaws) and the glass. It's obviously very important to have some kind of cushioning and extra grip between the glass of the window and the metal of the clamp.

REMEMBER you don't want to tighten up the clamp too much as you could end up breaking the glass

Whilst you at it I would also pump in a good spray of silicon grease (NOT WD40 as that evaporates) on the runners just to help dislodge any crud and make the electric windows lives a bit easier.

If there is no clamp, rubber or bolt then there is a strong possibility that it's all fallen into the bottom of the door panel and the other half of the clamp to the bottom of the runner, so un-screw and disconnect the speaker (Torx 20 bit needed) and get your arm in there to recover things and try and sort things out. Not sure how easily this will be to be honest.

Having spent last weekend taking off and swapping my door cards for nice Multi-van versions and then again as the bottom piece of silver insulation stuff shown above was not needed and was stopping the door card from being seated correctly, I reckon I could take a door card off, access the clamp, spray the runners and put it all back together in about 30mins flat..practice makes perfect I:

Oh and whilst I was about it I swapped the door speakers for some nice Infinity Reference "shallow mount" speakers T:

 

I suspect that one of the two glass clamps that hold the glass in place has become loose or broke.

Basically there are two clamps that grip the window glass that are mounted to a pair of vertical runners inside the door.

You will need to take the door card off (very easy just take your time) and then you will be faced with this :

o
As you can see I have shown two red arrows which point to two rubber access plugs, take these off and then this will allow you to see the two glass clamps when the window is wound about half way down.

There is an M10 (I think) hex set bolt on the clamps which is used to tighten the clamp up on to the glass. There should also be some black rubber shims/grips that sit between the metal part of the clamp (think vice jaws) and the glass. It's obviously very important to have some kind of cushioning and extra grip between the glass of the window and the metal of the clamp.

REMEMBER you don't want to tighten up the clamp too much as you could end up breaking the glass

Whilst you at it I would also pump in a good spray of silicon grease (NOT WD40 as that evaporates) on the runners just to help dislodge any crud and make the electric windows lives a bit easier.

If there is no clamp, rubber or bolt then there is a strong possibility that it's all fallen into the bottom of the door panel and the other half of the clamp to the bottom of the runner, so un-screw and disconnect the speaker (Torx 20 bit needed) and get your arm in there to recover things and try and sort things out. Not sure how easily this will be to be honest.

Having spent last weekend taking off and swapping my door cards for nice Multi-van versions and then again as the bottom piece of silver insulation stuff shown above was not needed and was stopping the door card from being seated correctly, I reckon I could take a door card off, access the clamp, spray the runners and put it all back together in about 30mins flat..practice makes perfect I:

Oh and whilst I was about it I swapped the door speakers for some nice Infinity Reference "shallow mount" speakers T:

thanks very much for all the info, will have a go.
were you by any chance selling the original door cards,i'm looking for the n/s card (obviously the electric window one... )
my ride is an ex builders bus and is being painted at the end of the month, i've managed to find a new (secondhand) o/s one thats in good condition, just need to try and source the n/s

 

Great post by Glitch, could have done with that a few weeks ago when I fitted my electric windows.

My passenger window was also getting stuck at a funny angle half way up. Sorted it by watching how it was getting jammed and then lifting it by hand as it was closing to see which was the best angle to get it to close properly. I then adjusted the window in its mounts as per Glitch's post, on mine the front of the window had to be lifted right up to the top of the clamp and rear section right down as low as it would go. Took a while to get it right but it seems to be working fine now.T:

 

Very old thread, but I have the same issue with the drivers window getting stuck - it seems that it is going up on a funny angle again low on the front / mirror side. I'm wondering if the fix proposed and done by 'Penn' has been successful long term? Out of my own stupidity I ended up having to repair my window regulator. Although only one clip had broken I had to replace all the cables and winding bobbin. I'd hoped that would have fixed the sticking window, but it is the same low / angled and have to pull up manually at the front. Lubrication alone hasn't fixed things. Grateful for any feedback.