Try a perch. Many birds are cage aggressive, or simply don't like stepping up on to a person when being removed from their cage, but will do so with a perch. I have used the plain, boring wooden perches that come with many cages (but I don't use in a cage, ever) as the perch to get such a bird to step up.
Also, if you're trying to remove them from the cage, try and get them to come to you rather than reaching in, have them come out onto a ledge, or on to an open door. Reaching in for removal can be seen as a sign of aggression on your part, and can cause defensive behaviors that we interpret as aggressive. We do not remove Loki, we open his door and he either climbs up on to the door, or sits at the bottom of the opening, and get him to step up from there. The only time we reach in his cage is to move things around, and obviously in an emergency we would reach in and grab him, biting or not.