Please be sure to tell them that the metal framing goes into/on the rubber molding PRIOR to installing the whole assembly in the car.
Additionally, 1/4" nylon cord WILL cut the new rubber molding. It needs to be thicker than the 1/4".
There seems to be an art to installing these older window glass with the aluminum frames. There isn't anything wrong with lots of lube.
Often, installers who are not familiar with the rubber molding (depending on the car and model) will not see that there are small flaps that partially fit over the aluminum molding which facilitates its final seating. Try to find a car similiar to yours and look closely at the fitting.
Good luck, keep us posted,
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)