This is a 1966 Merc 500 50hp 4 cyl. I'm trying to clear line to tell tale hole. I'm using weedeater line and got it to go in just over a foot, but no further. How far should that line go in? Will I be able to access it from below when I change the impeller? I have the prop in a barrel of water right now, and tried compressed air thru the hose from the top and there was no air coming out the bottom [no bubbles] so I am assuming it is really blocked. I'm waiting for my manual to come in before I tear anything apart. Any info would be greatly appreciated. There seems to be very knowlegable people on this site more than willing to help out! Thanks, Dan