How to diagnose an electrical problem?

"Firstly you will have to check the Battery by a digital multimeter. You can use analog also, but it will be heavy and may not give you the actual result. Then check the voltage with multimeter.

If okay check the coils and regulator. You will find error any one f these."

I solved this problem. I had identical issues. After a new battery failed to fix I got a new non sealed beam headlight. Didn't fix anything but needed one anyways… I then checked the blinkers because they did not blink and were very dim! In all blinkers I found somone had put 12v bulbs, replaced with 6v8w bulbs and now my blinkers worked again. Found out all my grounds had bad connections. Like really bad. In headlight case , under gas tank they added another ground that was loose. Probably added because they are not original blinkers that are not just 1 wire. Fixed grounds and while under the seat I checked all connections. Found out that a yellow stripe I think (maybe orange with stripe) wire comming from stator harness was barely connected. Fixed that and seen a little improvement. Finally the last thing I Fixed that was the cherry on top was that the blinker relay in headlight housing had gone bad. Not to mention, a 12v blinker relay at that! Perhaps causing electrical issues. Get a new 6volt blinker relay. Now all my lights are bright and working well even when I hit the brakes all because of a blinker relay. And because I hooked my stator back up I no longer needed to manually charge battery. Hope this helps someone. Grounds, wires connected??, correct bulbs and blinker relay! Walah. P.s. adjust the bolt very slowly on horn while somone is holding the horn button. If you don't hear a beep no matter which way you turn it then get a new 6v horn. $10-$20 Amazon. Treatland has a non sealed beam for fa50s. I bought a p15d h6m led bulb that works great from Amazon. Leds work with their beam. Make sure they are 6v though