When we moved into our rental 3 years ago, I paid to get the aerial replaced. I think it had probably been on the house for 20 years or so and it was covered in rust. The new aerial did the trick and gave us a perfect DTV signal.
By the way, if you're watching DTV through Play TV on your PS3, the signal is coming through the aerial, not the dish. The powers that be in New Zealand have confused a whole generation of Kiwis by calling the free versions of Digital Terrestrial TV and Digital Satellite TV both Freeview.