I've got a evinrude 6hp 70's vintage that I started with the muffs on. Problem is I can't find a tell tale and when I looked at the lower unit by the prop there is a square hole w/ screen covering it above and behind the prop. I put the muffs over the 4 holes on the side of the lower unit above the prop. Did I screw up and not get water in the right place? Did I damage my impeller? I'm not sure if I should use this or check the impeller first? Any advice would be appreciated.<br /><br />Thanks,