What was happening with mine was because it was sooo grungy that occasionally when I shifter, one of the arms was supposed to move and because there was so much resistence, and rub, that the arm next to it would move as well when it wasn't supposed to there by throw it into some in between gear. It actually would still be in first gear but I couldn't get the shifter unlocked. I would have to crawl under the car and manually move one of the shifter rods back into place, then it was good again till the next time.
