Here is how I open the Pyro motor to replace bearing.
The same can be used to replace the motor shaft.

1. First thing you need to remove the circlip (c-clip) with a spring clip plier.

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2. Then you need to remove a few shims (there may be 3 to 5 pieces), follow by a spring spacer.

3. Next, to pull the motor can (rotor) away from the stator (the winding block).
To make thing easier, I slide in two screwdrivers into the stator (be careful not to damage the motor winding)
and place the motor near the table edge (see picture below).
I then hold the two screwdrivers with one hand and hold and pull the motor can away with the other hand.

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4. Once you pull the stator and rotor apart , you can then remove the bearings on the stator.

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You can knock out the bearings using a screwdriver from the inside.
For the bottom bearing, you need to remove the two screws nearby.

Main Bearing: 6900ZZ
ID = 10mm
OD = 22mm
Thickness = 6mm

Bottom Bearing: 6800ZZ
ID = 10mm
OD = 19mm
Thickness = 5mm

5. To remove the motor shaft, you need to knock out the locking pin at the bottom of the rotor.