If tail looks OK I would just use it, the flex only happens under load and flexes back when load is relieved, Just make sure to always ck tail adj before flying and remember rubber bands will weaken, keep them tight for best responce. I am fixing to buy a ABX and will be making all these mods on it, buying it from a freind. He just bought it and I have been trying to teach him to fly but it is just too much bird for him to learn on
Good luck and Good flying
Ace