RCU Forums - Dynam fan trouble

Need some help here.

I bought a Dynam Me262 EDF jet. Problem is both fans seem buggered. The fans are both rubbing alot on the inner housing , and it looks like the factory must have run them as there is heavy scoring on the plastic and one blade is clearly bent.
It seems quality control is pretty sad at this factory.

I contacted the Hobby shop ( one hundred miles away, plusa ferry ride) And he said he would mail me new fans , but without motors, I would have to swap the old ones in.

So here is the problem, this Dynam 70mm fan has a large flathead screw infront of the blade, and must be unscrewed to get the fan off so as to get to the motor mount screws.
The screw just turns with great difficulty, but does not unscrew, just turns the whole fan blade, I have the back of the motor locked so it's not turning.
Attempts to lock the fan while uncrewing just bends the fans and tears metal off the screw slot.
I suspect the compression collet on the motor shaft is turning. The screw seems so tight like it has permanent lock-tight on it?

Anybody had this problem, and know how to get the blade off without destroying everything.?

Thanks for any help.

Tom