Are do it yourself wills legal?

Absolutely, but you have to do it right.  It's not just the words on the page, but also the procedure followed in executing thw will and having it attested to by witnesses.  There's no reason you can't do it yourself, but make sure you're familiar with the proper procedure and follow it.  Also, depending on how old the original will was, it is possible that relevant law may have changed, and you wouldn't want to just follow the same words blindly.