For about a week now every morning (temperatures are moderate at around 40-50 deg.), when I try to shift out of park, I have to repeatedly depress the thumb switch on the side of the shifter until it will eventually release and allow me to pull the shifter into reverse. After that, it works fine the rest of the day. Is there a way to unlock it as mentioned in an earlier post about the 2000 Xterra? Are there other things I can try? I have already had the transmission checked and it is fine. Thanks!