you could have several things going on.. weak motors, dirty tracks with dried up grease slowing it down,front guide roller misaligned. as to fitment, you can remove the interior panel and there are multiple adjustments available.. you can tilt the glass in by pushing the top track adjustment brkt outward .. there are stops in the track that limit upward travel, there are two bolts ,midway up the door, that allow you to rotate forward or back .. there are slide adjustments on top, that allow you to move the whole thing straight forward or back.. .. sometimes, tho, you may get it as close to perfect ,closing and operating correct, but still not fitting a weatherstrip..you will need to shim that weatherstrip .... I find the easy way to get close is to loosen everything, close door and put up glass.. get it right , then tighten all the bolts ..it can be a bitch, have patience