The booklet, I think, does not tell you how to remove and replace the lid that covers the tool bay.
Looking at my Miele cleaner now, the spring fits on two lugs about the diameter of a pencil. The two "tangs" of the spring point towards the crevice cleaner tool and bend downwards.
Remove the lid by flexing it off the lugs (if it's still attached) and fit the spring with the long straight edge against the filter. You may need a third hand now... Pull the long straight piece of the spring down towards the crevice tool and hold it with your third hand. With your other other two hands, flex the lid onto the lugs and let the spring go. Job done.
Remove lid - fit spring - fit lid.
Richard Buxton
October 2008