What is the fine-grained topic of the following text: It was in robot form when I bought it, and after discovering which exact one it is (Revenge of the Fallen Leader Class), then watching a great video on how to return him to truck form, I quickly discovered it's missing the windshield and muffler tips (not sure if that's what they are called) and possibly other parts. Only return the topic.
Returning a Transformers toy to its original form and missing parts