Broken blend door arm, how to change?

[87 WE2]

How does the plastic blend door arm come out? i need to change it.

 

[pacecarta]

look at the new arm , its T shaped where it pushes in , the hole in air box has slots
pull up and rotate old , when it hits the slots it will pull out

 

[87 WE2]

Thanks for the response Paul I didn't have a new arm here to look at. Ended up yanking the old broken ac box back out of the dumpster (that was fun) luckily they didn't pick up here yesterday. I lucked out the old blend door bracket was good so I cut the old one out so I could use the bracket and see how its mounted to the box wanted to get it off without breaking it.

Here's pics for future reference:

Where the plastic on the box bends the arm will be close to lining up with the bend. Thats the position the arm needs to be
in to lift it up and remove it.