You are using two different timer callbacks. So the last one that is being registered is overwriting the first one. You are better off using the vizact.ontimer function to register multiple timer events that do not conflict with each other. Your code would look something like this:
Code:
def ArrowTimer():
#Place code that updates arrow here
pass
vizact.ontimer(0,ArrowTimer)
def AvatarLookTimer():
#Place code that update avatar head here
pass
vizact.ontimer(0,AvatarLookTimer)