I had a thought that is probably what you already had on your mind- people are reporting this hoe unit is flogging out seals and is suffering from scored pistons. Now the only thing that can cause pistons to score is if they are rubbing hard against each other. This leads me to think that it's due to side loading, aka incorrect mounting just as you where alluring to. So if a proper part was made as you suggested then I don't think it would fail anymore.