Believe it or not having a 'zoo' like Sasuke had was a good thing.

He took the device back once Neji was done with it, putting it away and nodding, "Yeah. Kakashi already tried to seal it, but it broke while I was fighting Gaara of the Sand. Now it activates if I over-exert myself, as far as I can tell."

After a beat, he added, "Better than before. Before today, I couldn't access my chakra at all."