Hi All , I have just replaced both window  winder motors in my 350Z track . On looking up all the available threads to do it , I noticed all the hassles owners have to overcome to get the window up for the repair . I was desperate , when mine jammed in the down position before I was ready to fix it , and still needed to use it . I  started the motor , pulled the window switch up and banged the inside of the door panel roughly alongside where the motor is located . It jarred up the worn brushes for one last effort , and the window wound up much to my relief . I fastened two soft jaw Stanley clamps on the window to keep it from falling down again , while replacing the motor . One bit of advice I have noted on previous forums going forward , to avoid having to do the job again in the future . Is never to let the window go all the way to the bottom if you can help it , when using the window . It is a big heavy window , and needs a lot of leverage to move it resting at its lowest point . This is what prematurely wears the brushes out . That and try not to raise and lower the window with the motor off , this too stresses the brushes as the voltage is not as strong . Wish you luck , you can save a lot of money doing it yourself .

Thanks for posting this useful guide to replacing window motors....very helpful to other owners!