Derek, only 3 long bolts hold the Compact shell halves together - one exposed at the hose end under the bag door latch lever. The other two are inside the rear wheel wells and compress the rubber gasket surrounding the motor. Knock the axle pins out of the wheels ( they are knurled on one end and should be replaced in the same orientation when re-assembling - generally they are knocked in from the outer casing side but may have been earlier replaced and knocked in from the inner side), I use an Allen key as a pin drift or an appropriately sized round rod - they will pop out easily. Remove the wheels and any washers and the bolt heads are accessible.
Once the 3 bolts are removed the halves will separate - with a little gentle prodding - from the bumper ring, which may initially seem stuck in place. It is a friction fit only - no glue involved.
Separate carefully as the switch wiring often has shortened leads. The handle and foot switch lever can be detached from the body with the obvious 'drift pin' removed. Then the button switch can be removed for motor servicing without having to de-solder all the electrical connections.
The motor is held in place by a surrounding black rubber gasket ring that is tightly sandwiched between the shell halves and compressed upon blot tightening.
Note exactly how the gasket is fitted to the motor and how it is clamped inside the inner 'wall' of the shells...for easiest re-assembly.
The bumper ring gasket is an exact fit and so on re-assembly first fit the ring over the base half. The top shell half can be eased into place in the gasket groove with a slim DULL dinner knife if it proves reluctant to fully seat in the groove.
Dave