I've been inspecting the breather valves and it says in the Haynes manual that if it's a ball type breather,you have to check the ball. There doesn't seem to be any way of getting into it to see. I've poked out all the crap and DW'd it but I cant blow through it or anything. Is that because its a high pressure valve or should you be able to blow air through it? How do you know that it's not blocked?