Funny you should mention that air filter housing. That's the only thing (apparent) that's wrong with this mower; the hold down for the air filter housing is missing. Maybe that's the issue, that the hold down straps come loose and fall off.
Any thoughts on using it to cut the high grass in our meadows? This mower is actually a little more than we were planning to spend on a used piece, as we were also planning to try and pick up a used DR walk-behind brush mower. But if this Scag will handle it, then we can more readily justify the extra cost.