Are you saying only one blade is pitching when you apply throttle? It sounds like you're missing a link somewhere, so you're only activating one mixer arm which is why the flybar is pitching oddly and only one blade is getting pitched. Go over the build directions again very carefully. And make sure you have every control rod on. I just finished my build on my 600, and built my 450 about a month ago, and it's very easy to overlook a control rod if this is your 1st build.

As far as your tail servo, you may have your End Point Adj (EPA) in your radio set-up wrong, which may be causing you to lose throw in one direction, and overthrow the servo in the other direction. Check the menu in your radio, and make sure your EPA's are set at 100 for initial setup, and then adjust from there.

Check this link out: http://helifreak.com/viewtopic.php?t=15009. You'll have to register for the site, but this guy finless has videos that basically walk you thru every step of the build and setup process.

Lemme know what you find out.

Chad