I have a 1998 250 hp Yamaha OX66 EFI motor with about 800 hours. I've been hearing a slight noise that I haven't been able to pinpoint until today when it got much louder and started vibrating. According to my mechanic something let loose with the driveshaft or damper that will require him to almost completly disassemble the motor. I'm expecting his estimate in a day or so and I'm wondering what I should expect and if I should be considering a new motor.