Middle seat issues

[KGIA103]

I have a middle seat in an 86 6.9 f250...the seat folds up to a storage compartment and the back has a button/plunger on top that seems to be connected to a spring when lifted. What is this mechanism for?

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[jwalterus]

pull up, fold down

 

[KGIA103]

pull up, fold down

Must be broke. The plunger comes up an inch or so but nothing folds down.
Is this a stock Ford seat?