Turns out that autopilots are a great thing, they do a tremendous amount of work for you, quietly in the background. So what do you do if they fail? Mid passage?
If the seas are relatively calm you can get the boat balanced, lash the helm and check from time to time on your course adjusting as required. Its a problem but not a big one, as long as you know how to balance your helm with the sails.
But, if the seas are not calm and you have to continually deal with wave correction the only thing you can do is hand steer.
Your watch will have to be much shorter and You’ll need to have another on standby at all times because keeping on a steerage line whilst changing sails often takes more than a single hand.
NOTE: I’ve not had to deal with this yet, other than an outage of a few hours whilst an electrical problem was sorted, so I only know how hard it can be, not how are it REALLY can be.