Tim the motor is a 'push fit' - but we have always found them very tight to try and remove.
Our preferred method is to VERY carefully tap them out - we use a piece of copper (22 mil. dia. plumbing) tubing and a mallet, so that you are gently tapping down onto the neck of the casing not on the drive shaft. But bang it too hard and you will crack the case
To get it back we use sections of wood that will fit into the space and the bottom, and tap in several places with the same gentle, fingers crossed type of motion.
Having the whole machine in a nice warm room will also help a bit. The conservatory on sunny summer days was good for us.
Best of luck
Leila (and her helper Trevor)