Royalista
Unless your one of those people who like everything to be working, you might want to consider disconnecting your fuel level guage.
It's a very simple operation to just follow the wire from the sending unit and unplug it where it connects to the main wiring harness.
Then, you can join me and the others who jot down the mileage reading on the handlebars with a Sharpy black fine point marker every time you refuel.
With a little effort and some spit on my finger I can erase the old mileage value.
These failures make me wonder if the RE people are using the right type of alcohol in their fuel level sensor testing program.
If they are using something other than ethanol their tests could indicate they've found a good design but our fuels seem to ruin their best efforts.
ADB: I'm a bit confused but the Service Manual says that brake anchor plate nut is a M12 X 1.25 (part number 580368) although when I measured the exposed thread it measured slightly less than 11mm.
I suggest that you ride your bike carefully to a auto supply or a good hardware store and tell them your problem. They should have metric nuts that you could try on the stud. It will be a "fine thread" nut.
If you have the option, it would be best to buy a Grade 5 nut (or the metric equivalent) along with a washer.
The nut should be torqued to 18 foot pounds.