I have acquired an older Evinrude 15 hp outboard, not sure of the year. The model # is 1550 4C. The serial number is E000 8136. The motor has a low profile above the transom in white and two shades of blue. It is manual start. I was told that the engine was overheated and seized up. It turns over now but I haven't tried to start it. 1) How do you get to the impellor to replace it 2) Would it be worth it to have it bored out and new oversized pistons and rings installed? Do it myself? and What year is it. I was told that before it overheated, I was a great staring and running little motor. BB