Link: http://www.350z-uk.com/topic/88321-carried-out-a-rad-fan-motor-fix-today-small-how-too/
Link: http://www.350z-uk.com/topic/69810-how-to-repairfix-your-cooling-fan-motors-youtube-vid/
If you do find that you need or want new fan motors then a popular upgrade option are the Mishimoto fans.
Link: http://www.350z-uk.com/topic/87662-mishimoto-replacement-fan-kit-350z-vq35de/