The bellows are tight. There are just long runs of push notes without pull notes.

Well, start those songs with the bellows pulled open about 10 inches and see how it goes. And check the ball of your thumb on the left hand and see how it interacts with the air release on the back of the base side buttons. Some accordion players are pushing that air release valve constantly, while others seldom use it....it's supposed to be subconscious, lol....don't go thinking about that air release valve too much. You have way too much other stuff going on while playing that accordion to have to think about that air release valve too. Unless you're like me....I think about all of it and none of it at the same time while playing.