Vespa PK50XL2 (V5X3T)

Hi!

I need some help with my Vespa PK50XL2

The horn does not work and the fuel gauge is stuck on empty. Everything else seems to be in order with the electric system, and it starts and runs like clockwork. Indicators, hi/lo beam, pilot light, rear light and indicators on the speedo work fine. Any suggestions?

Regards.