Modern Vespa

I am new to this and have a Stella 2 stroke scooter..
It had developed a gear oil leak on the right rear...can some point me in the right direction as to where to start
Its a 2005

Are you sure it's gear oil?

Mine had a horrible leak that turned out to be a bad oil injection pump gasket. The oil would pool in the carb box and leak out through the plastic air screw plug on the back of the airbox housing. Changing all the paper gaskets around the carb box, and not overfilling the oil tank, solved the problem

If it is gear oil, start with simple things. Drain it, replace the crush washers on the drain and fill holes, and refill with the correct quantity (250ccs). There's also a gasket between the selector box and the gearbox.

First of all, though, thoroughly clean the area with Brakleen or solvent of your choice. Put a pan under the suspect area and see exactly where the leak is coming from. That'll inform your next steps.

Pics would help