the pope

I have a nib JR 2610 and upon installing in a new plane I noticed a problem with the pull pull rudder where the rudder would not centre propery and it would appear to reach its end of travell and then move a bit more.Anyway to cut along story short I replaced the servo and made sure there was no binding etc and then I tried another plane and it does the same thing so there is something wrong with the transmitter.Any ideas what my prob. is. Thanks in advance the pope