Still following the thread but not got a lot of input other than FFS.
Mine goes off occasionally but only when I change dip to full. I can turn off the ignition switch kill everything and back on again normally before I have to bump start the engine. All is then ok.. I have stopped flashing people as it can kill the headlight. It's very intermittent. I was thinking it was the relay that you have not used. I understand that these kits suffered from flicker and would expect the black box that coaster so kindly showed opened up, to have some thing more than a simple relay on off. Caps ore normally used for smoothing out voltages, the large zenner diodes are also used to stop voltages going up and down and one way. With my relay it took a feed from the battery, I didn't use it as I took it from my rear light, only on when my lights are on. I wanted to still keep the battery isolated so as not to drain my battery. Again mine had a male h4 socket and I was thinking the power was coming through the light switch but from what coaster is saying the switch mAy only be operating the flick flack.
I can only hope that when it was working it gave the light you are seeking. Stick at it.