Hi,What Radio are you useing???? I herd of problems trying to use recievers with more than 4 channels ,dont know for sure,all my full function Tanks are over sea japanese releases,that come with futaba radio systems all set up already.Try a radio like Futaba Attack 4ch (ground) thats whats included with the Tamiya kit I have.Also check the Trimms and try setting and resetting them.
let us know how you make out...