Xbox 360 right analog stick won't work? Is it just time to buy another xbox?

I'm having an issue where the analog stick won't work for my niece while she plays minecraft. I'm also having an issue where some of the buttons arent even mapped right in some games. For example, crazy taxi has rt or rb to accelerate and a to go backwards but rt and rb go backwards and the other buttons don't do anything at all. I thought buying another controller would fix this but when i got back from gamestop and started using it the same problem occurred. I have an xbox 360 slim model and have had pretty much since 2011-12 i believe. It also has issues playing games on discs. Some games the audio unsyncs and the framerate drops and some games just freeze completely on the title screen or something. Any ideas?