I know exactly what you mean! How you fix this depends on whether or not you have the heavy duty motor installed. I'm assuming that you already have the heavy duty motor installed, because mine did the same thing. If I roll the window up all the way, it makes a jack hammer sound like the clutch on a cordless power drill. When I roll it down all the way, the window travels farther than it needs to. I saw a fix for this on someone's web site. I don't remember who it was except for he is a list member and is in Europe somewhere. Basically, the situation is that at least some of the aftermarket heavy duty motors have a design flaw. The tube assemblies on them were made too short and now they have to reach too far to get to the window glass. When you roll the window down all the way, it goes too far down. And when you roll it up all the way, the flexible cable is too short and leaves the sprocket gear that drives it. The ratcheting sound you hear comes from the sprocket gear teeth slipping on the end of the drive cable. To fix this, make an extension piece to fit the end of the cable. Use a swatch of sheet metal about an inch square. Drill two holes in one end (that match the top of the window motor assembly) and drill two more holes on the other end to match the studs on the bottom of the window glass. I also used two 1/4-20 bolts, nuts & lockwashers to connect the swatch to the end of the drive cable. Be careful that the new nuts & bolts are positioned so that they don't catch on the top of the tube when you lower the window. This solves both problems: It effectively makes the drive cable longer so that it doesn't slip past the drive gear, and it also stops the window glass from lowering too far into the door. I made this modification to a heavy duty window motor that came with my car. I didn't know it was the heavy duty model because I assumed that all heavy duty motors didn't have problems. Well, think again. When it completely quit working, I was ready to replace it with a heavy duty model only to find out that it already was the heavy duty model. Enough water got inside of the new motor that it rusted it up and ruined it. Fortunately, I was able to buy a used motor and keep the rest of the heavy duty assembly. This brings up another very important caveat: When you install the heavy duty motor, BE SURE TO REMOVE THE DRAIN PLUG! That is why my motor went bad. These Bosch motors come with little plastic drain plugs. You are supposed to remove whichever plug ends up on the bottom of the assembly. Otherwise, if water gets inside the motor, it won't come out. Keep the plug installed on the top to help keep water out of the motor. I may get a bit wordy at times, but I think my advice is worth following. Later, Walt Tampa, FL