R170 door window adjustment

[GadgetBoy]

1998 SLK230K

I've done a search on the forum and the internet and I can find many articles describing adjusting the windows for the closed position. My problem is one of my windows won't open fully.

The left hand door window (passenger side RHD) stops about 25mm above the door top. Where is the adjustment for the lower position?

 

[GadgetBoy]

The plot thickens. This picture below shows the problem, the window doesn't open fully.

I thought this would be some simple adjustment but it turns out the glass is not fully located in the bottom slot. Next image.

You can see on the left hand side there where the rubber gasket isn't down inside the bracket. The glass itself could go another 15-20mm deeper into the bracket.

I decided to leave it alone and ask for advice from you knowledgeable lot. Putting reasonable pressure on the assembly results in the glass not moving at all in the bracket. I don't want to put excess pressure on it because I don't want a broken window.

Any ideas?