L322 Driver window seal

Hi, I've got a 2007 4.2 supercharged which is fantastic but I'm having an issue with the driver door window. When the window is opened all the way and then shut it will often run on the wrong side of the door A post seal, when the window gets to the top of it's travel it is then massively misaligned with the casement and whistles like mad. I've had the door panel off but it is very difficult to see anything, the only way to get it back in the correct 'guide' is to pull the glass towards you as it's closing, and minding your fingers.
Does anyone know of any adjustment that might be possible, there is no slop or movement in the glass and the seals appear to be in decent condition.
Many Thanks Ian

Sounds like the lower window guide has come adrift.