I removed the driver's rubber weather stripping completely to clean the old lubricants and gunk. I ran window up/down when NO rubber and it worked ok until midway, it was binding (with NO rubber strip on!). So that's why I thought my BACK/REAR track may be causing some binding, but with flashlight I just couldn't see where. I put the rubber track back in and right now, it's perfect with silicone spray. Up/down very fast. Passenger side looks like previous owner may have removed entire rubber strip....will be checking it out soon.