In the above video it provides detailed instructions on how to replace the starter on a 2003 Infiniti G35. You can get a replacement starter for an Infiniti G35 over on Amazon for around $69 plus shipping and handling.
The replacement starter mentioned above is a TYC starter that was built brand-new to meet Original Equipment (OE) specifications. The bearings, brushes, armature, field case assembly, solenoid, starter drive are all 100% new, providing longer service life than remanufactured starters.