Just wondering what food you use in it? My dog is normally on a raw diet and I couldn't think of anything compatible to use in it which wouldn't clog up the mechanism. Now she's temporarily on kibble, we're using that in it, but it's not high enough reward value for her and she loses interest very quickly.
If you don't know what the Manners Minder is by the way, it's a gadget designed by Sophia Yin - it's basically a robotic/remote control treat dispenser, and you follow the training programme DVD which comes with it to teach the dog to settle on her mat in certain situations (mainly when visitors come to the door, but you can also use it in other situations such as teaching dogs not to resource guard etc). It's fab! I got mine from US Amazon:
[http://www.amazon.com/Premier-Manners-Minder-Behavior-Training/dp/B0010B8CHG/ref=sr_1_1?ie=UTF8&qid=1344512647&sr=8-1&keywords=manners+minder MannersMinder]