Hi Max and BT,
The sheared key can be directly related to the fact that the mower is relying on the spinning weight of the fly/fan wheel instead of having a good blade carrier to do this work.You only have to look at a Victa F/C on an 18 inch base and the same motor on a 24 inch machine, the big 24 inch blade carrier is doing most of the work making it a far more powerful machine