@Faber32, good to read again of you.
This oilseals (there are two) on your swingarm act, to protect one of your REAR wheel bearings which houses within this mentioned part.
It does NOT protect your scoots gear from loosing oil.
Dimensions are 30-40-7 mm and 30-48-7mm, both are standart metric oilseals, inexpensive and easy to replace. And yes, take new ones.