Abstract: A method of replacing rotor windings of a dynamoelectric machine having aluminum windings with copper windings having the same number of coil turns and of about the same weight as the original aluminum windings wherein the copper rotor slot conductors are positioned at the top of the rotor slots and are supported in the slots by a U-shaped channel element to form an integral subslot for providing a supply of cooling gas to the windings. The copper windings, turn insulation, creepage block and slot wedges including aligned openings to form radially directed ventilation passages for directly cooling the windings by a flow of cooling gasses from the subslot through the radial passages to discharge in the airgap between the rotor and stator of the machine.