Where can I find a part for my lift chair motor?

I have a Lazy Boy Lift chair #7190-0939 Type 90B1, 115 volts,Hz 60,2.5 amps int duty E53469 E46205. The motor was manufactured by Maxwell Products Inc in Cerritos Cal. The small plastic worm screw in the motor is broken. Where can I order that part?

ALVIN J LEJEUNE, November 2013