Hi Blue,
I must say that it is a rather strange one. The ally cover is rather free and can be easily rotated around the nut and there are holes through it that correspond with the 3 fine threaded holes in the housing. (flywheel) It's as if there should be 3 long bolts that should be wound into the holes and through the ally cover and pushing against the washer to pop the nut assembly out of the housing, would that maybe be the case ?
Cheers,
BB