I just bought a set of new window rollers for my '67 SS and after they came, I noticed on the old ones that the stem that attaches to the raise/lower assembly is kind of 'smashed' in to the arm. It almost has a star shape to the back side. The new parts just have a stem that will fit thru the hole, but the question I have is, How do I 'smash' the new posts into the arm so that it will stay, and given that I will have to have the plastic roller in place when I do this, how do I protect it from damage?

When I took apart my door panels and replaced my window rollers, I had the same problem. All you have to do is position the new window roller in the hole, and give it a good firm tap. Don't worry, you probably won't break the plastic washer, and if you do, it won't affect the function of the roller. Good Luck!