I have a 64 El Camino and one of the windows will not stay up. I took the door panel off and saw that the piece of rubber which fits on the bottom edge of the glass has broken off in pieces and therefore the window mechinism will not grab hold of the window. As you can tell from my description I am not well versed with auto repair. My question is where can I purchase replacement rubber for the window bottom. Of the speciality shops I've checked they only have weatherstripping. I would appreciate any advise.