Originally Posted by Wirespokes
The reason for removing the spacer is clearance - the switch needs more room and the spacer interferes. The rear of the engine needs to be supported, though it'll be close to balanced on the front one. A jack makes it easier to keep the engine bolt from binding when withdrawing and replacing.
So essentially the engine doesn't need to move whatsoever in the frame, only the alloy spacer. You don't need to lower the engine just loosen the front support rod and remove the rear, spacer comes out and swap the switch as per Snobum....