240D manual window regulator installation
 

I'm wondering if anyone knows the installation instructions (beyond Haynes, which I have) for a manual window regulator for a 1982 240d.

I already have the panel off, the old regulator out, and a new one in there, but I can't get it to align with the window properly. It can go all the way up, but the back side of the window and the arm it should fit and stay in (the trunkward side) aren't touching.

I suspect there's some very specific way to put the regulator in (a certain crank position?), but I appear to have it in okay: it moves up and down fine, but just won't allow the window glass to sit on it and move up and down with it.

Any help would be greatly appreciated.

Thanks!