How to motivate students to debug their work independently
One way that could work is to open a forum or a place for the students do help each other. This would prevent posting incomplete or not clear questions (because no one would like to look dumb) and would help you to debug once for class (maybe you could also collect them and provide it for the next courses). You could then also grade the activity on the forum (at least that helped me to post in a forum for a lecture :).

As tonysdg suggest you could let them know the rules of the forum like in Stack Overflow. Or say that if they (or other students) can't solve their problems in a week (or two) you will step in.

The most important part is let them know how and what do you expect from them before coming to you.