I am pleased to report I did get the Orgoblo unit apart [000709 MMD].
I took a piece of plywood with a 1-1/4" diameter hole in the center,
and a 1-1/4" diam. pipe slipped over the motor shaft, and tapped the
hub of the fan, and it did move slightly.

I soaked it with WD40-type oil spray and was able to rock the fan on
the shaft a bit, but it wouldn't come off.  Rocking it let the oil
spray work in and turn a brown rusty color, which indicated there was
some rust under the hub.

So, I thought I'd block the motor from turning and try "unscrewing" the
fan, and that worked perfectly.  There was just a little surface rust.
I also found there was a second fan, behind the baffle plate, that
wasn't obvious the first look-over; it was tighter but it came off the
same way.

I'm _very_ happy I don't have to haul it out as a unit -- the motor
alone weighs about 175 pounds.

I was advised to mark the shaft before removing.  There is a score line
for alignment and the hubs have a mark, but the unit must have been
opened before because the fan marks were not aligned with the shaft's
score despite the warning label instructing to be "dead sure the two
line up".

It didn't appear to be pressed on.  On this unit there is an aluminum
bracket that has four rubber bumpers and fits between adjacent fins,
with two bolts that clamp the motor shaft, that holds the fans IN and
from spinning on the shaft.

I would guess too that a press fit would be difficult to service in
the field.  Logic told me that something this big and heavy, no matter
what, would have to have a reasonable expectation for field repairs
by ordinary organ technicians, and it seems I was right.

So now I have the unit dismantled, the motor off, and cast iron motor
mounts out.  I guess the drum is about 150 pounds and 36" diam. by 32"
deep, so the next adventure, on Saturday, is getting it down a winding
flight of stairs 33" wide with tall cast iron newel posts.  :)

I have a room made for it on a raised concrete slab in my basement,
down yet another flight of stairs, but much wider than 33", thankfully.

Randy