i just bought some window channel weather stripping for my 73 GMC 1/2 ton 2wd. it is not working as planned. when i get it put in there the window won't roll up or down. I've looked for it to be binding but i dint see anything. I also called JCWhitney where i got it and talked to them and ckecked the #'s and it is the right one. any hints?