Steering Damper td5 ???

Can anyone discribe the symptoms of a faulty or failed steering damper.
I,ve had slight steering wobble at certain speeds and the steering sometimes has a loose spot or play. I have tightened up the steering box and checked the tyre pressures and balance. The steering joints all appear to be ok. Any ideas ?? Cheers

Hit a bump in the road and the steering wheel will 'shimmy' left and right for a second of two is one symptom, the only way to test is remove it and pull and push it apart to see if there any flat spots in it's travel, if there is it's shot. Standard replacements are not expensive.