A method, including: replacing an original blade shelf (16) of a gas turbine engine blade (10) with a new blade shelf (64) that is located closer to a base (18) of the blade than the original blade shelf; adding mass to the blade until a mass of the blade with the new blade shelf is greater than a mass of the blade with the original blade shelf in order to maintain a same contribution by the blade with the new blade shelf as a contribution by the blade with the original blade shelf to a dynamic balance of a rotor arrangement.