I need help! I recently bought a broken 15hp 1979 and fixed it up. It worked great! One day I was on the lake and it all of a sudden it locked up. A screw came loose underneath the flywheel and siezed it to the spark timing plate. It also cracked the coil. Removing the flywheel and replacing the coil I'm trying to get it started again and it will not start. Spark is good, compression is good, spark is good, carb has been recleaned, and new fuel is being used. What am I missing here???