RE: problem with ARk X-400
yes, it's 120 degree, and itll fix the sloppy elevator problem.
eccpm requires 3 HIGH QUALITY + MATCHED servos. if you dont have this, it wont work right. your TX must also be capable of supporting a 120 degree swash. you might be better off buying the metal lever and elevator system.
however it is the best upgrade for the x400 IMO