I am trying to learn Fur Elise on classical guitar using this video:

as a reference. I am doing quite well in the first and third movements as they are quite easy to play, however a specific part in the second movement(1:44-1:47) just bums me out. I am 90% sure it is my left hand technique, as I can play 1:42-1:44 up to original tempo. Is there any specific technique used here or is it just lack of practice?