interesting nss problem

This 91 beater I've inherited has a problem with the NSS. That's not a surprise really, but what is interesting is that it is only a part-time problem. If I go out and try to start in park while the engine is cool it will start fine. But if I drive anywhere at all enough to get the engine warm it will no longer start in park and I have to switch to neutral.

Maybe it's just off a hair instead of broken/filthy? It's like 20* out there so I'm playing arm-chair mechanic and not gonna look.

I know the newer NSS can adjusted. The large nut holds it onto the shaft and the small bolt allows for adjustment. With the Key on and engine off, the parking brake set, put the transmission in reverse. Loosen the small upper bolt and twist the whole NSS until the backup lights come on. Tighten the small bolt back down, just past snug (you don't want to crack the NSS housing). Check that the XJ only will start in Park and Neutral. Done.

Probably just needs removed and cleaned. There are a few good writeups with pictures. Try searching for Go-Jeeps writeup, or google for NSS cleaning.

Cleaning it is on the list, but the fact that it only does it when the engine is warm is kind of odd since it suggests a really minor failure.