If everything lines up and you have N start and back lamps in R , then your NSS is going bad. The contacts are about had it.
If the shifter bushings are gone, then the rod will not be able to push the NSS all the way to P position b/c the shifter hits the stop gate before NSS engagement, but that is not your problem as the bushings do not have any slop.
Change it before you loose both N and P contact........

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A Dalton