Complete Vespa smallframe engine strip down and rebuild.
10. Replacing seals.

There are three oil seals in a smallframe Vespa engine. One that seals the crank from the clutch chamber, one that seals the mainshaft at the flywheel and one that seals the rear axle at the hub. Whenever you rebuild the engine you should always renew the seals. It's false economy not to, and when you take an engine apart you never know what state they will be in.The hub seal and the flywheel seal can actually both be replaced with the engine in the scooter as they can be accessed from the outside, but the clutch side seal can only be replaced with the engine split and the crank out of the scooter. When pressing a new seal into place it's important to make sure it goes in the right way and to make sure it goes in evenly. Here's where the clutch side one goes

And the flywheel side:

And the rear hub seal:

In each case the face with the spring in faces into the body of the engine.