Might need to relieve the side screen height a bit, I use 120 grit wet and dry around a rubber sanding block kept well lubricated with warm soapy water.
You could also check the channel is absolutely clear - when I did the same job on my 1971 car, it seemed the factory placed a very thin packing strip under the lining material - bit difficult to see at first but picked out with a scriber!
Arwyn