[cypher]

Don't know what to suggest really, I've only had one who bites & I do have to be careful just how I put my hand in her cage, she's fine outside the cage, it's never too late to go back to basics with taming though, even doing the tissue trick for some time might help them realise that your scent just isn't going to go away & biting won't help!
Do you handle them outside the cage?
Sometimes it just takes an awful lot of patience & observation to see how best to interact with them.