There was a Comic by Dark Horse, about side characters through out the Movies. One of the stories was about R5-D4 being Force Sensitive. It even went as far to say he for seen that R2 should be the Droid for Luke, so he blew out his own Motivator knowing that he may never be reactivated. That way Luke would take R2.
yeah that is skippy who is non canon, but it is still a good story