The driver's side window on my '49 1/2-ton stays up while the truck is standing still, but works its way down while driving. Is replacing the spring in the window regulator a weekend project? I've also noticed that the window is not square to the frame. One edge of the window reaches the top before the other when rolling the window up. The regulator has elongated holes where it is mounted to the door, but no matter how I install the regulator, the window does not track squarely in the window frame. This doesn't seem right.