BG Mazda 323 Hatch manual window sticky HELP

[Waugh-terfall]

Hi all, the drivers window in my 1993 BG Mazda 323 Hatch 3dr has always been hard to move near the top but today in the pouring rain it got totally jammed half-way up and it took about 10mins of manhandling to get it up. Does anyone know how I might solve this problem, am OK with a screw driver!

Thanks in advance