I have a NEO and recently I had an issue. No air flowing. Yes, I cleaned the heck out if it. I then did some diagnosing and realized it was the valve. I called Iwata and they sent me a replacement valve body (no charge) and now it works great! I may have gotten something down in the valve, not sure but they didn't even question me, just sent a new one.
If I had it to do all over again, I would have spent more money and bought a Revolution or an Eclipse. I will say that I was very impressed with Iwata's customer service.
On a related note, I left my air brush to soak in restorer for a week by accident (long story) and the disposable cup I used just melted. What a mess!