Yaris T Spirit (2007) 'Clicking' Steering Concern

[gwswindale]

Last month I bought a 2007 Yaris T Spirit (only 12k miles on the clock) and it's been great. But yesterday, on a long-ish journey, after about 50 miles I noticed the steering started feeling awkward. It felt like it was 'clicking' when turning the steering wheel past the centre point - ie when facing roughly straight. It wasn't making making a noise that I could hear, but I could feel it clearly through the steering wheel.

Took it for a short drive this morning and it wasn't evident this time, however I wonder it it only occurs on longer journeys. Checked tyre pressures too and they're fine.

Any thoughts and suggestions are very welcome!