I bought a fishing boat with a Merc 350, I felt like the motor was locked up but the deal was so cheap I bought anyway. I checked the flywheel and it would not move at all. Before giving up on the motor I decided to put some WD-40 down in the spark plug holes and see if it would loosen up, so for three or four days a few minutes a day I have been trying to move the fly wheel with a hammer and screwdriver, and wd-40, today it moved. By hand I can move the flywheel an inch or so in both directions, with the hammer and screw driver I can move the flywheel about 3 or 4 inches in both directions. I could have continued with the hammer but decided to stop and let the wd-40 work some more. when I move the fly wheel I can see both pistons move thru the spark plug holes, and the prop also moves. My question is am I waisting my time, is there any hope for this motor without a rebuild. Thanks for any help.