front brake light switch is in housing behind the brake lever, rear switch is on left side of bike( as though you are sitting on it) under the oil tank, just follow the brake line as it is a hydralic swith "T"ed in to the rear brakes
its located on the trans .. its a plug .
On top of the steering column. ////////take a look on the transmission
It's on top of the brake pedal under the dash.
Base of the steering column.
The 1980 Suzuki key code switch is located near the ignition switch. This is the common location for most older models.
go to Sportster forum at http://xlforum.net/vbportal/forums you can find a lot of answers to your questions
Yes! Usually at 5000 mile intervals.
undeer the center console trim.
Gearbox selector sleeve wear - which might not be helped if the primary is slack.
strictly circut breakers and they are under the seat in front of the battery, there will be 4 in total
Check the fuses? Check the light switch?
I have a 1988 420sel. I'm not sure if they are the same but I have a slide switch just to the right of the overhead light between the sun visors.