Bad Emag Battery???

[spyderxtra4]

Ok everyone heres the deal. My brother was using his emag saturday and some reason it isn't shooting right. It works perfect in mechanical mode. When he shoots fast it shoots the first 2 shots then it won't shot anymore, then if he waits a few seconds it will shoot again. It won't shoot everytime he pulls the trigger. Now remember it shoots perfect in mechanical mode. We don't think its the battery because we put a voltage meter up to it and it is fully charged and is giving off energy. I tried searching but there are too many people on pbnation. Any help would be greatly appreciated.
Thanks