Welcome to FlyerTalk.

As a former pilot, I'll concur pretty much with what has been said about aircraft weight and balance issues and why four passengers were selected for voluntary denied boarding. And as a former navaids - comm global troubleshooter, I can tell you radar units can be easy or very difficult to repair (and some specialized parts might have to be requisitioned and shipped from the specific aircraft's and company's maintenance base).

For you quest for compensation, I suggest reading at least the Wikiposts at the top of the page in the following threads:

http://www.flyertalk.com/forum/ameri...er-thread.html (link).

http://www.flyertalk.com/forum/ameri...solidated.html (link).

(As your question is primarily about compensation, we will ultimately merge this into the campo thread to minimize information fragmentation and facilitate members' finding germane information when they search. /Moderator)