My 20 year old b17 has developed an irritating noise from the nose cone. Have greased or proofhided everything I can and checked every other likely area from seatpost upwards. My guess is the tension bolt is cracked but it is still in place As it sounds like metal on metal. Has anyone replaced a tension bolt themselves? Or, I might treat it to a full Brooks rebuild as the rails are also a bit rusty. Anyone used that service?