If you are missing episode credits, you will need to submit your credits for the missing episodes through our online Update form.
Credits on episodic TV shows must be submitted as additions to all individual episodes of the show, multiple episode submissions for the same credit are easier if you go to the main page of the show and click on the 'Edit Page' button. After selecting 'Add 1 Item' next to the correct type of credit, you will be presented with a screen where you can enter the name of the person and an 'Episodes' field. Clicking on the 'arrow' icon next to the 'Episodes' field will display a list of all known episodes for that show: you can select all applicable ones and submit the same credit for all of them at the same time.
For more information about adding/updating credits, please see here.