Pond Pump problem

Hi,

I have a Hydor 24 volt submersible pond pump, where the pump rotor has
become detached from the motor shaft. before I take the risk of wrecking the
casing, Would any of you know how to gain access to the motor? There are no
screws that I can see. There is a plastic "diverter" in front of the plastic
rotor, which blocks access to the rotor. At the rear, where the power cable
exits, there is a cover which seems to be pressed on, with no visible ways
of removing it.

I would appreciate comments from anyone, especially if you've tackled one of
these pumps.

Thank You.

Henry Mydlarz.