>>408383158
As far as improvements, chest is okay. elbows dont seem to do much for me as the fov of the headset makes it so i dont see my elbows anyways. knee tracking is pretty good without trackers. but since you only have the one chest is the only option. the quality of IK also depends on the bone of the avatar. if its not setup right the chest tracker can make the IK do funky things. 

anon posted a guide on how to change the batteries on the 2.0 trackers but i doubt that will fix ur issue.