5-4GBF.Engine vibratesexcessively.1. Propeller damaged.1. Have propeller repaired or replaced.2. Propeller shaft damaged.2. Have serviced by a Yamaha dealer.3. Weeds or other foreign matter tangledon propeller.3. Remove and clean propeller.4. Motor mounting bolt loose.4. Tighten bolt.5. Steering pivot loose or damaged.5. Tighten or have serviced by a Yamahadealer.TroublePossible CauseRemedy