Yesterday I had a worker mowing and apparently the oil dipstick was loose. Oil came out and engine over heated and shut off. He let it cool for over an hour. He put oil back into it and it started back up. Everything seems fine except sometime when I engage the blades the engine bogs down. This doesn't happen everytime. Just wondering what might be causing this? What things should I get checked out. The mower is a Ferris procutz 61 with a 23horse Kaw on it and only has 80 hours on the engine. Thanks for any help.