Loose heater box?

Also good call on the J hook being the problem for the loose heater box. Thanks gang. On the three heater control cable hookup is it right that one of the cables goes to an arm on a heater box that's in between the tubes coming from the heater core I believe? Also on the fresh air door I took off to get to the J Bolt it was screwed on by somebody is there supposed to be something that has hinges on there so the store actually opens and closes properly? Sorry for all the questions hopefully I am getting ready to get out of this heater box nightmare! Thanks again gang!