Fairly new at this hobby so please be kind...I've recently purchased a jen91 after running it in with no issues...I maidened my seagull extra 300s with the jen91 up front. Flight went with out a hitch,but on the cleaning down I've noticed slop,a small amount of play on the prop shaft rocking back and forth with a knocking noise from in side the engine,I would appreciate any advice.thank you