1980 KZ750 H

I picked this up in March with 23k miles. valves adjusted, APE cam chain tensioner, fork oil and seals replaced, brake pads, fluid and rebuilt wheel cylinders, rebuilt petcock, replaced fuel filter, air filter, synthetic oil change/filter, spark plugs, battery, sprockets/chain changed to 530 16/38, replaced dash, headlight and tail lamp with LED's. Carbs jetted and cleaned. Handlebars and mirrors changed. Seat redone by Pirate Upholstery. It starts without the choke and pulls like a freight train to the top end. Progressive shocks and springs done by former owner. I have 2 things left to do. Coils are overheating and I will replace them and wires with Dyna 2.2's. The high beam switch seems to be working, as indicated by the instrument panel, but it is not switching the bulb on. I changed bulbs to see if this one was defective, but nope it is not the bulb. High beam was working when installed. If anyone has some troubleshooting advice for this, it would be greatly appreciated. I know very little about electrical circuitry.

I can't say I'm familiar with the 750. I have a 650.

If the wiring is similar, then the high beam position connects both the high beam filament and the the high beam indicator to 12V. Both the filament and indicator have their own grounds, so one can work even if the other doesn't.

I believe this is the correct wiring diagram?
kz.bike-night.com/media/KZ750-H1-US.jpg

Looks to be the same, just a bit more cluttered,
The high beam indicator and the high beam filament are switched to 12V in parallel. So one can work without the other.

I guess I would start at the headlight and make sure the three connections, specifically the red and black wire, are secure.
If you have a multimeter, you could remove the red/black and black/yellow wire and check for 12V when the switch is on high.

The LH control switch has got lots of sliding contacts. I took the units apart on my 750 and cleaned out all the corrosion and lubed the parts with dielectric grease. Found one broken wire too which was resoldered. Pay attention while taking the control apart but don't be fearful.

Good luck.