Paul,
The Ronstan telescopic tiller extension is great until you bend it a few times or once badly. I have given up on the expense and gone to an aircraft grade aluminium alloy which is both light weight and very strong. It's a whole lot better than the spagetti from Bunnings and comes in 5m lengths so you can pretty much cut it in half and have a spare as backup. I'll try to get more detail on the supplier.
Regards,
Peter