By way of background, basically the bike worked, then worked with a loss of power, then stopped working. At present it will start one in a hundred times, cranking for a long time before doing so and only with the throttle open, and will then quickly splutter to stop.

At some point, the plastic bit that you screw into the tank, where the pipe that leads to the fuel injector joins on, has been repaired. I think it is still airtight. I replaced the TPS as I know XT 660R's had an issue there, and also put in a new battery, but no change. The electrical stuff seems okay, there is no fault code. I'd basically narrowed it down to blocked fuel filter or blocked fuel injector (the gasoline is so dirty and the air so humid) but I don't know much about bike other than reading the manual!