Modern Vespa

Got home from 3 months of travel with 150 on a battery tender that failed and boiled all the water out of the battery. New battery and engine starts easily but the starter is not cutting out some of the time. Riding over a nice bump fixed it yesterday. I ain't checked nothing yet. Going to be this afternoons project.
So, where should I start?

The starter relay has decided to weld it self shut intermittently - more common than you might think, I've had three do this...

Cheap enough to replace, and the Vespa relay can be opened up and the contacts cleaned.

If that doesn't fix it it might be a sticky bendix. The stater bendix gear cluster is located behind the outer variator pulley. You have to remove the transmission housing and variator assembly to get to it. Here is an excellent video on how to gain access to the bendix:
http://www.youtube.com/watch?v=jiEA9SXhtng&feature=youtube_gdata

A sticky bendix won't stop the starter motor from cutting off when it should...

I must be misunderstanding what he is experiencing...

Thanks Jim. I think you are right and thank you for the advice. Tested a few things then pulled the relay, cleaned the contacts and but it back in and now it does nothing. So, I went to our new Vespa dealer in town Barneys Vespa returns to St. Pete and ordered a new one.
They said 60 scooters showed up for the opening ride and free food. They were still out on the ride, but I got 3 free Vespa pens.

MV is, as we all know, I wonderful source of maintenance knowledge and help. Even if I know what the problem is I will throw it out here just to get it confirmed by knowledgeable people. Just as I did with this one. So I decided to document my problem in hopes of helping others.

The symptom: Starter stays engaged all the time even with the key removed. You have to disconnect the battery to stop it.
The cause: Bad starter relay

This is a easy fix. You can pull the relay and take it's cover off and clean the contacts if you want to try it. This is simple. If that does not cure it you can just install a replacement relay for $16 +/-

PROCEDURE:
Disconnect the battery.
Remove the rear cover by removing the 5 screws and the gas cap.
Pull the relay.
Replace with new relay.
GOOD LUCK.