Thomas & Friends S01E04 - Edward, Gordon & Henry

Based on the story of the same name from The Three Railway Engines.

Henry has been stuck in the tunnel for a long time now, and wishes he hadn't been so silly. But one day, Gordon goes too fast and bursts a safety valve right in front of the tunnel. Edward is the only engine available, but he can't push the heavy train without Henry's help, so Henry is let out.