The side mounts are adjustable. Just wind them down until your rear mount is centred in the aperture in the bulkhead.
Why they are like this is difficult to say. One would have thought that if anything, they would have dropped the rear mount until it touched the bottom of the aperture rather than vice versa.
The bobbin mount could be worn, as indeed could the volume springs which can lose their resilience. This might result in clutch judder and an engine that moves about a lot when decelarating.
I see that you are also into Amazons. I have a PV 544 for when I get fed up with Gallic engineering.