Modern Vespa

I just put a new windscreen on my GTV. There's not a whole lot of space available on the handlebars to mount a bracket, with the brakes, cables and whatall already on there. Apparently in tugging at the cables to make a bit of room for the bracket I must have pulled something loose. Now when I try to start it, it will only work with the right brake engaged but not with the left. Before I go pulling things apart to try to solve the problem I thought I'd check here first so you all can tell me I'm missing something very simple.

Coincidentally, when I did start it for the first time after the windshield installation, it idled roughly for a minute. It wouldn't maintain steady revs, but went up and down. It idled low enough that I thought it might stall out. After getting on and giving it some gas a few times that problem went away but it was kind of strange. Related or weird coincidence?

TIA for any advice, suggestions, ridicule, etc.

Well, there's a brake light (electrical) switch on the brake mounting - they control both the starter interlock, AND the brake light. So, if your's isn't working it means your brake light isn't engaging for the front brakes either.

Edit: Here's a pic from Danny*h's LX150 showing the two of them on the brake mounts:

LX-150 Audicator Installation - With Pictures

Bingo! I had pulled the wires out on the brake lever. I couldn't see or feel that they were loose because of the boot that covers them. I was hoping it was something like that since I didn't want to have to pull the headset apart.

Many thanks, Harvey.