I think you would have to replace the whole thing, part 28 in the diagram, to have any sort of guarantee of a fix - you can't really tell if the fault is in the actual rack or the motor assembly.
Now, this is a bit of a long post, but bear with me.
A lot of people say that the Jazz steering is poor, but you can live with it, and that it's just a characteristic of the car. I don't believe that these owners are experiencing the issue we are talking about here. We need to differentiate between the 'normal' dead steering feel of the mark 1 Jazz, with its poor centreing and lifeless, woolly feel, and a
different problem which is a sticky, rubbery feel that makes it difficult to steer the car in a straight line. The former is simply a characteristic of the Jazz EPS system, while the latter, in my opinion, is most definitely a fault.
Our 2008 car definitely suffered from the latter, once the car had been driven for a while. When it was stone cold, the steering felt 'normal', but after a few miles, it started to develop the sticky rubbery feel where if you held a particular steering angle for 10 seconds or so, a significant input of force was required to turn the wheel - when it would suddenly 'give'.
I regarded that as a fault, and this opinion was further reinforced when I managed to 'cure' this by accident. I'm not sure what I disturbed, but the car was completely cured of this odd problem, and has remained so ever since.
https://clubjazz.org/forum/index.php?topic=10179If you think that what you experiencing is just the 'characteristic' of the car's steering, i.e. the lifeless feel with poor centreing, this can be improved by toeing in the front wheels a little, towards the toe-in end of the acceptable range of 0 ± 3.0mm. After playing with the tracking on the front of the Jazz, I found that anything towards the toe-out end of the' tracking range made the steering feel, and particularly the centreing, much worse - but toeing in a bit, away from the target of zero, improved it no end.