I wonder if this goes deeper--and this is random speculation that doesn't mean anything at all and shouldn't be taken seriously--but perhaps there aren't any spare parts, and the trucks/equipment/etc are being eaten alive by the desert...
The "no spare parts" meme is pretty consistent in all US operations in Iraq. After all, why would you need maintenance when you're going to be mostly out of the country by January 2004?
(snark over)
