Window Motor problem

Anyone have any suggestions as to why my passenger side window motor has died twice in the last year? The 2nd motor I put in has only lasted about 6 months. The windows does go up/down more slowly than the driver's side.

Check alignment of the glass and guides (they're adjustable). Clean the regulator tracks and re-grease them with white lithium grease. Clean the window guides and apply a thin layer of clear silicone grease to the bare rubber guides. If the mechanism has a balance spring (some do), make sure it is intact.