I have a Gravely 144z with about 240 hours on it, and have to replace the left wheel motor and wheel hub, as the key in the axel which prevents the wheel hub from spinning on the axel, allowed movement and wore its slot out in the axel and the hub. Luckily my crew manager noticed the excess tire movement before any further damage happened. In talking to the dealer I found that one of the other units they sold had the same problem, and also damaged the braking system on that model after the wheel broke loose and twisted. The wheel in question is the one opposite the blowerside, which is the wheel motor which would sustain the most abuse as it is the one which is normally on the inside of your turns around trees, beds ect. So it would suffer the most stop and go action, which puts pressure on either side of the axel key. My question is if any other Gravely owners have had the same problem, as it appears to be a defect in manfacture which has allowed movement on a part which is susposed to prevent it. My serial # is within the first 200 manufactured, which might have a bearing on it. I would appreciate any input.