I was trying to remove the plate behind the front end crank casing to replace that gasket. I put great torque with a gear puller as well as a crow bar to remove these gears. I did notice that the crank shaft gear did move forward a fraction of a mm. Not sure if it was the gear or the whole crank shaft. I didn't get the gears off and gave up and put it all back together again. But now when I run the engine there is a knocking sound at the bottom of the engine. Any ideas what could have caused this?