MY BOAT IS A 1977 EVINRUDE 75 HP. I DONT EVEN KNOW IF THE IMPELLER HAS EVER BEEN CHANGED. I BOUGHT IT FROM MY UNCLE AND I KNOW HE HAS TAKEN GOOD CARE OF IT. IT RUNS GOOD BUT I KNOW I NEED TO CHANGE THE IMPELLER BECAUSE IT WAS NOT RUNNING TWO STREAMS OUT OF THE THE TOP. S0 I TOOK THE 4 SCREWS OUT OF THE STREAM AND COULDN'T GET THE FOOT TO EVEN BUDGE. I HIT IT WITH A HAMMER ON A CLOTH AND STARTED TO BEND THE STEEL. PLEASE GIVE ME SOME ADVICE. IS THERE ANYWHERE I CAN SPRAY WD-40 TO HELP? OR ANY ADVICE GREATLY APPRECIATED.