I have a 1977 yamaha 650 and the tail light won't work. The break light works but when I turn the key all the way to the right it won't start it has to be in the middle. Any ideas?

I don't know if this helps but I once had older bike that kept vibrating the key out of ignition I whould start it and then put it in my pocket eventually I discovered that I needed the key in to complete the charging circuit