I have an 87 FJ60 that all four door windows are very difficult to open to the point of wondering if the handles will break. One of the rear windows drags the rubber track with it when lowering. Is the rubber inserts the only reason for this or is there another probable source for the problem. I don't want to disassemble the doors more than once. Is it possible to rejuvenate the tracks or is replacement the only option? Also what is a good source for these window parts?