Hoover Fusion Plus Vacuum Won't Recline

White trying to diagnose a separate problem (needs a new belt, it turns out), my Hoover Fusion Plus vacuum model U5183-300 won't recline. I step on the green recliner lever and it won't go back.

Any help is much appreciated!

I'd love to have this corrected by the time the belts I just ordered from Amazon arrive.

Thanks in advance!