Well, this may be a switch for the old fellow, but for his safety and your sanity you may want to start crating him when you aren't there to watch him or catch him misbehaving. He's not too old to learn new tricks, you don't have to spend hours trying to train him either. You really should only spend 30 minutes to an hour a day training cause any longer than that and he'll get board with it. You may want to try finding a trainer who knows how to teach dogs with hand signs. Using treats will be a big plus in traing him now, cause his eyes and knows work so he'll be focused on you and that treat. A good trick to start with is getting him to make eye contact. Get his attention with a treat by waving it in his face, but don't let him have it. When he's focused on that treat, bring it up to your face and with the same hand the treat is in, point to your eyes and say "eyes". He may not hear you, but he sees your mouth moving and giving a command. When you can keep his eyes focused on yours for a few seconds without him looking away, give him the treat. Make the focus time a little longer every time. This trick will help you with other obedience lessons when you need him to watch you give a command. Since he has lost his hearing, when you catch him doing something wrong, you can squirt him with water to get his attention. When he's chewing on things that are not his, trade that with something of his own like a favorite toy or chewy.