When did Curly start to slip?

I've thought the first signs of seeing Curly slipping was in the 1944 episode "Busy Buddies", Curly seems to be slowing down a bit in that episode, oddly he seemed to be healthier and more energetic in some of the later released episodes like "Gents Without Cents", "No Dough Boys" and "Three Pests In A Mess".