Having done two Zane fuel pumps with rotting internal fuel lines I'd have to say it's one of the most absurd design features I've seen on a bike. Big deal, so it's nice and tidy, but no matter how much the bike is ridden, those lines are eventually going to fuk up. No thought whatsoever to the future. How hard would it have been to design them with an external fuel pump FFS?!
You might be able to find some liquid agent or an acid that will soften and clean that crap, Andy. Or put the whole effing tank in a furnace and burn it out.