Abstract: Methods are provided for modifying an airfoil internal cooling circuit that include a flow path configured to direct air through the airfoil in a direction and the airfoil having a leading edge, a trailing edge, and a first and a second wall therebetween, each wall having an inner and an outer surface, the inner surfaces defining a cavity and having features forming at least a portion of the internal cooling circuit. The methods may include the steps of forming a pilot hole through the airfoil first and second walls at a predetermined location, forming an insert hole based on the predetermined location, the insert hole enveloping the pilot hole and configured to receive at least a portion of an insert configured to modify the internal cooling circuit flow path, placing the insert into the insert hole, and bonding the insert to the airfoil first and second walls.