Driveshaft differential V7 Special 850

Finally bought a new Guzzi V7 850 Special and I"m interested to know if there is meant to be small (2mm ) gap around the circumference of the rear wheel differential. It allows me to see inside and to view a lightly rusting disc which I presume is a rotating backplate that holds the crown wheel of the differential. I’d always thought the diff was a totally sealed unit . I hope that I was wrong and this is normal.
Please forgive my ignorance but would appreciate feedback. Cheers Tim

No worries - found a good film on the internet after a search on repair and maintenance of the shaft drive.
Cheers Tim