Left one is fine, you can just use the other bit, or even solder onto it
When you say the right one is loose... do you mean you can kind of twist it? if so thats fine too as long as the wire behind it is still connected ok
If you've got an old speaker lying about you could take the terminal off that and solder it on, thats what I did with my sub which I got off a mate for £10 cos he thought it was knackered