I had an issue a few years back now, with my then FZS600, Lights would just cut out while riding, including the rear light, brake light continued to work and my engine kept running.
There is on the FZS600 at least a large white plastic connector/junction box under the petrol tank that connect most of the cables in the main wiring harness loom.
water had gotten into this junction box at some point and had caused a bad connection on about 5 of the wire causing them to corrode, they had gone green with verdigris and had been partially eaten away.
This in itself caused much struggling try to get the two halves of the junction box apart.
I cut the wires either side of the junction box, bared both ends the wires and made up a number of 100mm long link wires, slipped on heat shrink and then soldered the links in to the loom, bypassing the offending connection/junction box.
The only downside to this would be should the need arise to remove the loom from the bike, IE: should you want to re-stove enamel the frame.
I'm not saying this is the issue but its worth a thought.
Your issue seems to be an intermittent one exactly the same as my lighting one, the hardest faults to sort out.
It certainly cured all my wiring issues.
Good luck and I hope you get the 1K sorted soon, summers almost here.
tommyardin