2004-2005 660 Yamaha Rhino Factory Service Manual, Page 252Get this manual
TROUBLESHOOTING CAUTION:
Too little gear lash is extremely destructive to the gear teethIf test ride following reassembly indicates this condition, stop riding immediately to minimize gear damagecA slight "thunk" evident at low speed operationThis noise must be distinguished from normal vehicle operationDiagnosis: Possible broken gear teethWARNING Stop riding immediately if broken gear teeth are suspectedThis condition could result in the shaft drive assembly locking up, causing loss of control of the vehicle and possible injury to the riderLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL