Bob in Phx writes:

Keep using the motor until the gear is so loose that I can pry it off
and then "glue" it back on.

Likely burrs on the gear and grooves on the shaft from spinning the gear
are going to lock it on. It will take a properly fitted gear puller to get
it off, and sometimes this means custom making such a puller. You can't
pry or hammer against the motor bearings without ruining them.

JB Well-Duh is just epoxy glue with a stupid, lying name. If steel didn't
hold up, glue with 1/20 the material strength certainly won't.

Perhaps this is a Chinese item? Improperly engineered for the actual
instantaneous torque experienced in the assembly, which has nothing to do
with the torque rating of the motor. Silk purse, sow's ear.