Tivo box pixelated picture

So we've had this tivo box for quite a number of years now and over the last few months the picture has becoming pixelated every now and then. It also sometimes freezes and crashes as well. And one more thing it takes an age to start up when its been switched off at the plug. I'm not sure if we need a new tv box or the wires outside need rewiring as it has some nicks in the wire and part of the wall it was attached to is broken so some of the wire is just hanging out. I'd imagine we need both doing but any help would be really needed. 

Many thanks

Michael