Speculation only......
Looks like that particular motor is shot. That would call for a replacement of that motor.
I never built a hobby drone. I never tried to repair a toy drone. I know nothing about repairing a drone of any version.
I went to aliexpress and found this for you .....
A screenshot of SG906 Max pro front and rear motor arms replacement from Aliexpress.
(Note: The price quoted is in Canadian. It will be different if you are from different country. The price is for 1 arm, not 4.)
Caution : You drone has 2 A arms, one of which is for the FRONT, and 2 B arms, one of which is for the FRONT. Make sure you purchase the correct arm.
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