now that you said its like something is wrong with the channel so then Id say replace radio. and there are other radios cheaper if you look.. Id get a 3 channel radio. read manual b4 installing in max
have you swapped servos around from ch1 to ch2 then vis versa?. if you haven't and ordered a new radio then that was a was of a item to buy. get a cheap servo tester and try all servos b4 buying radio.