[folivier]

Did you pull off the valence at the inside of the slide? That allows you to see the hanger bar. It might be worth putting in larger sheet metal screws along the bar if Newell didn't do that already. They did on mine when they adjusted the bar.
I found that if I'm not pretty level when extending the front slide (even in travel mode) it would sometimes not grab the hanger bar. You can see the middle of the slide lift up slightly when it gets to the end of travel if it does engage it properly.