I thought that the motor on my window of my 1973 cs was going bad. I took it apart as suggested and the moving parts were all gunked up and mostly not operating smoothly. I took all the moving parts out and cleaned them and put the window back together. now it works great. However there was a chase that runs vertical with a set of metal wheels that keep the window in place as it moves. This chase was full of a thick grease. I did not replace it because the window seems to function well with out it. However the window rattles now. I am pretty sure that it is the metal wheels in the chase rattling around. Does anyone know if the grease is necessary and what kind of substance it is?