A friend's 69 chevelle SS is having problems with the manually operated driver's side window. It goes up and down fine. When all the way up, it feels loose. You can move the top of window in and out at ease. Really aggravating when driving as you have a bad air leak at the top. Any way to tighten this up? He has already taken it to a glass shop and the painter of car unable to diagnose or fix problem. Any suggestions?

Thanks,
Lou 44888