well i don't know much but from the looks of it the motor is fine
t its just the power needed to bring the window up that isnt there, therfore it would be amp
and dude check this out i googled 240sx window amp.......and then it suggested "window amp repair" i clicked it and lookie here
Repairing Power Window Amp: 240sx Articles: Nissan Forums / Infiniti Forums - NICOclub