My mother was told years ago that her built in ventilation system would need to be replaced as the fan had broken. I plugged a light into the socket inside the system, and it still works; all I need is the motor assembly and I'm having trouble finding one. Home Depot says they only have hoods; the internet has been of no real help. She has a Trade Wind Motorfans, Inc. system, but they apparently are no longer in business in Los Angeles. Where can I buy just a fan? She doesn't want a hood when she has a built in.