Window Won't Roll Down

[jim-bob]

I'm wanting to remove the window and vent window on my 67..but I cannot roll it down to get the vent window out..The most it will budge is 1 inch..It feels like if i keep putting pressure on it the handle's gonna break..I really don't believe it's seized up by rust beings as high up as it is..There's rust at the bottom of this door of course but this truck doesn't have very must rust at all..It feels like it's binding..The other door window is easy to roll up and down..Should I remove the 4 screws that hold the regulator or loosen them..I've never removed windows in these trucks..Your advise will be very much appreciated.