I dont suspect anything may be loose, this seems to be kind of a common issues with this model, some people has written a bypass way of this way and such, but not sure how exactly is done. every other light is working fine.
to re confirms the issue, when I start the bike, put the headligt on, it stays on, and when i rev the bike the headlight brightens up and in a couple of seconds goes off entirely. so this is the issue.
below are some other peoples post on same issue
Riding home Tuesday night, I hit my high beams. After about 3 or 4 seconds, my headlights completely shut off! When I switched back to low beams, still nothing!
When I stopped though, the dim mode came back on. As soon as I started moving again, they shut down again!
So I turned the scoot off for a few seconds, hoping the system might reset, and it worked! My low beams were working normal again. I tried the high beams again, and it all shut off again.