Place a washer on each
of the long screws
While holding the weld nuts in place, slide both screws
through the washers, motor mount, motor and screw into
the weld nut. For the moment, leave the screws loose
enough so that the motor mount plastic can wiggle a little.
With the screws a little loose, press
down against a flat surface, so that
the both bottoms of the motor
mount are flat.
Keeping the bottoms of the motor
mount flat against the surface,
tighten both screws. Do not over-
tighten, you may crush the motor.