Kz750 LTD only one side of hazard flashing

Well the title says it all, only the left hand side of the hazards flash when the switch is pushed to the H position. Both relays are modern electric ones and click good. The turn signals work great on both sides. The rear turn signals are 1156 single filament so it rules out a burned bulb because the turn signals flash. There’s only 2 wires going to the bulb so the fact that turn signals work means the ground is good for the bulb. It has to be a power issue getting to the bulb, but for some reason only the right hand bulb. Any ideas? 

Given your description of the fault the possible causes are very limited, see below. It can only be the switch or the wiring between the switch and the splice on the grey wire, anything else would effect turn signal operation or both sides of the hazards