2006 Honda TRX680 Rincon Factory Service Manual, Page 459Get this manual
FRONT DRIVING MECHANISM Turn the mm nut and check the pinion gear turns smoothly and quietly without bindingIf the pinion gear does not turn smoothly or quietly, the pinion gear, ring gear andor bearing may be damaged or faultyThey must be checked after disassembly; replace them if necessary
BACKLASH INSPECTION
Hold the pinion gear with the mm nutSet the differential case into jig or vise with soft jawsInstall the differential inspection tool into the right side of the differential