Bought a new engine from the dealer to repower my 737, 23 hp kaw. About 3 weeks ago machine started losing power under load and dealer discover that it needed a new head. This was warranted by them, and got machince back. Now same problem seemed to be happening so I took into dealer to have them trouble shoot. They told me needs new coil, not cover under warranty. I installed new coil, which did inprove the engine performance a little, but still lose of power. Back into the dealer. Now they tell me that the key way is missing that holds the fly wheel in place for timing. Not covered under warranty. Should this be warranty? Would they need to remove fly wheel to do a head job on this engine?