2003 350Z window problem

Most likely your window motor has failed due to dirt inside from normal wear and tear during use, or overloading has burned it out. A second possibility is that you need to reset the calibration on the motor that tells it when to stop at the top and bottom (also necessary after replacing a worn or burned out motor). Great service-manual-quality info can be found here (link is to the reset procedure). Door panel removal is here. Window motor service info is here and here.

I have the same problem, It belive is the window regulator motor, I open the door panel and kick the motor couple time, then press the switch if works. My window work after that, but the problem came back. I need a window motor . But its a temp solution if you have some mechanical skills.

I had this same problem with my 03 Z. To fix remove door facing, and crash plate. You can find a diy on how to remove the lift motor. Once you have removed the lift motor from the car, there are 3 screws that hold the casing together. Carefully remove the metal shield. DO NOT touch any of the parts with bare hands. There will be a shaft inside the shield that will have a cylindrical copper contact plate. This plate is probably black from the carbon brushes in side the shield. Again very carefully with the finest grit sand paper you can find softly sand the copper back to its original color. Put the motor back together and reinstall it in your car. A word to the wise. Make sure your window is down when you do this and mark the cable harness and the motor so you can realign the motor and the cable crank, other wise your window will not realign properly and it will roll back down when the automatic button is hit. This process is tedious but I promise it work. Or well it worked on mine.