[Apex]

My guess is the switch. The bulb was replaced, and it was not the problem. We can rule that out. Your fuse keeps blowing, yet it is designed to handle the amperage of the bulb, something is dragging it down. So it is something else in the circuit. A corrosion problem would most likely cause it to work here and there...we get corrosion or oxidation on a connector, and it drops voltage across the union. Most likely not the cause.

I'd say the switch. Relay's tend to either work or not work. I have never found one to short in all my years working on electronic circuits. I've wired up nitrous systems and they either work or they don't. Same goes for the multi-million dollar equipment we have here at work.

Hit up the switch. Another possibility is the wiring from the switch to the light. Your bike is a '94, so the cable could have rubbed itself a contact patch that only hits when you apply power to the high beam.

Inspect the wiring. If there is nothing visible, I'd take the switch apart, run a voltmeter on it (set to ohms) and check for a short (red to the cable, and black to the bike chassis). If you have it, then replace the wiring, if not replace the switch.

It could also be shorting to another wire, so you may read an open and still have a short. So we can't rule that out.