my 2 cents
if the glass is that rusted, don't force the handle/regulator, it can't take that much and will deform/stretch the gear teeth and will be sloppy forever more or the aluminum handle will strip on the spline.
i suggest hands on each side of the glass and try to pull it down, get it to move that way
the glass is much cheaper than the regulator assembly if you need to break something price out all the parts first, because i saw prices like $70 for the regulator, but the glass i can get those for $30 at my local glass shop cut-to-pattern
-s
