Modern Vespa

The same happened to my hpe GTS after 5k miles, but on the opposite side. The mechanic discovered it during the annual motorcycle inspection.

The shock had never been removed after I purchased the Vespa.

I missed the earlier picture in this thread. Mine looks quite different, or am I not seeing this correctly?

The shock in question is the one on the right-hand side (exhaust side). Some bikes only have one shock - I believe your Sprint is one of those.

Yes, my sprint 150 has but one shock and it is securely attached!

It's not quite the same thing if it happened on the other side of the bike. Sounds as if your bike wasn't pdi'd properly or the bike has been tampered with.

Early models didn't have the big washer, or a nyloc nut, they had a shouldered nut that was nipped to become locking.

Please this way Sir...

Looks like the bushing slipped off the shock. Seen it happen a few times. There was quite a number of Piaggio scooters that had a smaller OD washer instead the bigger one that prevents this. Old washer was 10,4x18x2mm (part code 016627). Newer one is 10x30x2mm (part code 013962). I always changed them to the bigger ones. They were most often found on the 200 Beverlys. Maybe a supply issue at the factory, so they used what they had at the time??

That's interesting. None of the parts lists that I have or have seen online show the earlier one but it must have been very very early they used that and only for a very limited time. So it must mean they did away with the smaller washer very quickly when they realised it was pants and dangerous!

I have seen a few scooters where this has happened, and all were without a large washer.The bushing will come out if the washer is smaller than the metal bushing surround.

Not pdi'd properly is possible, tampered with, not very likely. Maybe it's just that a wrong sized washer was used at assembly. Surprisingly the ride quality wasn't affected that much.