mate, Im not sure what you are trying to say? I do not want to appear rude but if you do the basic setup of a digital servo connected to the nose steering via cables you should not have a problem with straight steering, and using your radio for sub trim to the steering so as to centre it, and when retracted it should go up straight and down. Even when the nose leg is going down the cables should take up the slack and keep the nose wheel straight.

Ive never come across this problem myslf I hope I have not affended you.

regards
Todd