Modern Vespa

Changed the headlight on my LX150 (2006) the other day, but in trying to remove the cowling, unscrewed a long (2"+) bolt (nice machine bolt) that was dead center underneath the headlight. It didn't seem to release or loosen anything, so I put it back in, but now I'm wondering if it isn't some kind of setscrew or adjustment screw. Don't want the front end to fall off! Anyone know what this is and is just screwing it back in ok?

I believe that finely machined screw is the pivot control of the headlight up/down adjustment. I accidently removed it similarly replacing a headlight bulb (on my ET-4) and had quite a time getting the screw's rounded ball end to snap back into its receiver (it popped free, and did not reattach when the screw was fully removed). Not 100% sure it's the same on the LX models? If you can reinstall it easily that's good, but check the headlight alignment. I had to remove the cover and get the screw to reattach so I could adjust the headlight aim upward

https://modernvespa.com/forum/post1452570?highlight=#1452570

Yep he screw you removed was the headlight aim adjustment screw. A Haynes manual shows you how to set the correct aim.

How do you remove the round headlamp cover? Do you have to remove the entire cowl assembly again?

And thanks to you both! I'll ride better knowing the handlebars aren't going to come off in my hands! LOL

You do have to remove the front part of the handlebar cover,
Take mirrors off first (17mm spanner)

There are three screws, one is covered by the horn cover. Flat screwdriver to prise the piagio badge off, remove horn cover screw. Then you will see another screw BELOW the one you accidently took out. The final screws are on the other side diectly under each handle. There are tabs on each side of the cover so carefully wiiggle it off and it should now be free.