Happy New Year !
IF you can not obtain the AC motor part from Yaesu USA
or from Ham Radio Outlet (HRO),
THEN You CAN rebuild (rewind) the existing AC Induction Motor.
The Azimuth and Elevation Rotors use the SAME AC Induction Motor !
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During the Japanese Parts Shortage, following the March 2011 Tōhoku Earthquake and Tsunami, Dave Palmer, KB5WIA faced the identical situation.
He documented the DIY Rewinding of that AC Induction motor in March 2012.