rack & pinion steering gear replacement

[rangerbot]

I am nut sure how the steering gear works but I have seen how to pull it on utube but it did not really show how to check if the remanufactured rack and pinion assembly has to be centred.

I know you have to lock the steering wheel so it cannot turn freely as there is a spring inside the column that gets destroyed.

So does the new rack need to be centered and how is it done.

Thanks in advance.