Forgive this description, we are new to small engines! My son took his engine apart trying to take off the governor. Then gave up and put it back together. While running, it froze up and we took it apart and saw that the push rod was bent and piece of the head was chipped where the exhaust valve goes in. So, have replaced the head, rods and a bad valve that must have been bent a little when it froze. We also went ahead and put new valve springs on along with a head gasket and valve gasket. Its starts fine, idles fine but goes very slow and cannot get up a hill. I can feel air blowing out of the sides like a bad gasket or seal. I am trying to figure out what is causing this loss of power. I used the old crankcase gasket - could that be the problem? The push rods are identical on this engine, I think? Valves are set to .003 so wondering if they should be re-adjusted. Any help is appreciated!