Leave ESB Yoda be. Maybe do some 'Cantina' work to his mouth and eyes to add more blinks and marginally more articulation to his lips. Note the word 'marginally'. I'm sure we all want Yoda to look as magical as he did in 1980 (which is weird for me to say, since I'd have been -9 years old then, but I'm sure people will agree).
May the Force be with you, Ady, in fixing those sound channels.