Upon disassembly, the source of the noisy operation became evident: the bearing on which the motor shaft rides was shot, which allowed the motor shaft to wobble in an eccentric manner, causing the noisy operation. An on-line search led me to AppliancePartsPros.com and after entering the make and model of the refrigerator, I was able to find the replacement motor by scrolling through the exploded view of the freezer evaporator fan. That exploded view is very helpful when re-assembling the new motor to the frame which mounts it to the shroud. The parts came exceedingly fast and the re-assembly went off without a hitch. Note: Remember to reattach the green grounding wire from the harness to the bare metal part of the assembly for electrical safety.