Here is the solution some ingenious contractor adopted (ebay picture):

[Linked Image]

This is a worn out HRU215 for sale on ebay. If you look at the red circle, you can see that the base has worn so severely that the front axle has moved forward more than an inch. If you look at the yellow oval, you can see that it moved all the way until the center part of the axle hit the front flange of the base, and couldn't move any further. Looking at the green circle, to make this possible the fore and aft link of the height adjusting mechanism has been extended more than an inch by welding in an extra bit. After that, you couldn't adjust the height any more, but the axle couldn't move any more either.

That base has been used for so long that the front of the scroll that confines the air and grass under the mower, has been just about worn all the way through and is falling to pieces.

Maybe that mower belongs in a museum of Australian ingenuity.