KitchenAid Artisan
KSN150ps

Machine has little use.
Motor Vibrates
Inpsected unit and discovered that the bearing bracket nuts are vibrating loose.
I tighten slighty - noise goes away and mixer runs smooth. But they loosen quickly and vvibration and noise returns. If I tighten to 15/20 ftlbs per the manual - the motor wont turn by hand - so i have not tried to reassemble and run at that applied torque .

Any recommendations...fixes? i would like to double nut, and lock washer this - but there is little room for 2 wrenches to tighten 2 nuts in this manner

mixer is fine if i could just get the bearing retainer nuts seated and not back off due to vibration.