Check the rotation direction. Very often the threads are LEFT-HAND, i.e. you
turn the plastic piece to the right to loosen it. A rule of thumb that seems
to apply in these cases is that the motor will turn in the direction that
would tighten the blade on the shaft, not loosen it, so you need to turn the
blade in the direction that the motor turns to loosen it.

There's also often a nut screwed onto the same shaft above the fan blade.
Whichever way removes the nut is the way you need to turn the fan blade.

Bob M.
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"Dr. Doctor" wrote in message
. ..
you are right they are designed to remove items that are screwed on and on
the item in question the end of the armature will have a slot in it for a
screwdriver in it to hold it or it will stick out far enough so a soft jaw
vise can hold it.
Sticking something into a fan blade no matter how substantial is not the
proper way and will always have a risk of doing damage. these unit in
question here do not have a hole to lock the armature / rotor with a pin
of
sorts. this is more common on weedtrimmers to remove the spool assembly.