1981 Honda CB 750C electrical issue

Hi, I have a 1980 CB750c, for about 8 years now, when I got it. It had sat out for over 4 years and had similar issues. The fuses would be a good start to check, also wiggle them in the holder or run some scotch bright pad through the fuse holders and fuse ends if you find any corrosion. I found that several of the connectors had corrosion and wiggling them caused the light to come on. I found a battery cleaner/ protector (in spray can) that cleans the green corrosion off the connector without to much work, I think it was "Permatex", it cleans chemically and you can leave it on after, that's how I did it and It's been fine for years .The other place that causes this problem would be the light switch itself. You can disassemble it and clean those contacts inside it. corrosion is often the problem on 40 + old machines. I have a Suzuki that had head light issues, and the switch was melted and I had to replace it. This old Honda is probably my favorite old bike to ride, it's reliable, comfortable and does every thing I need it to do. I hope you can get yours sorted out too.