Thomas & Friends (1984)

S1E18 Coal

Henry has been experiencing persistent sickness, setting him apart from the other engines. Upon investigation, it is discovered that his firebox is significantly smaller than theirs. To help him, the Fat Controller arranges for a special supply of Welsh coal, designed to improve Henry's performance. The Green Engine is overjoyed with the positive changes that follow, feeling revitalized and ready to take on his duties with renewed energy.