Actually the motor/axle is loose...
The issue is that the motor is too big to pass through the crown gear
I presume that the crown gear has to be removed... but have no idea on how to do so
Unless there is another way ?
Guessing only (do not forget that!), as I have never had the need to dismantle a hub motor (long may that remain so!), but guessing only, the manufacturer placed that gear in a freezer, also he warmed up the outside of the motor case, before placing the gear inside. Probably before the rim and spokes were mounted.
To reverse this is going to be difficult (I hope that someone here has a PROPER answer for you!)
My thoughts are, plenty of WD40 (or similar) around the contact area between the gear and the outside case, then put a "Puller", with the feet reversed to pull on that gear, and see if you can get it moving! But do not damage the cable to the motor while doing this.....
Or using a hardwood block, try tapping the motor shaft and see if it moves the gear outwards.
Possibly warming the outside case with a hot hair dryer at the same time.
This is a 2 man job.
I myself feel that you may simply need a new motor, (count the spokes and make sure a replacement motor has the same number!).
But they are also available with a premounted rim, from various sources. Make sure that it is compatible to your controller, if you have to go that way....
My very best wishes for a speedy and relatively cheap fix for you, one way or another.
I do not envy your predicament in the slightest.
regards
Andy