G'day Daryl,
Not familiar with this mower so don't really know what is normal or not. Did have another quick look and noticed the motor was a little loose on the chassis. I think the mother-in-law took it to a mower shop and was told it was dead at some stage so they may have mucked around a bit. Once I re-tighten everything I'll have a good listen which may be hard as it is pretty loud as the muffler probably needs to be changed. Haven't changed the 'O' ring. Its different from the powertorque (half crank v Full Crank?) so not quite sure how to tackle it.