Ganimal.. do an inspection of the regulator first. Check to see if there is any cracks or defects. Check to see if the teeth on the regulator are worn or not. Check also where the plastic tabs, they are white in color... and these are the parts that connect the regulator to the window. If these are OK.. check the motor next. I would simply check by hearing sounds if its running. There is probably an electric tool/device that does this, but don't know the name.