1986 WD Preference AP20 for Mac Plus

I am trying to revive a WD Preference hard drive AP20 used with a Mac Plus. I believe the head drive is stuck. BUT I cannot fathom how to open the box.
Please help.

get a new disk for the old mac plus

Actually I think the WD Preference AP20 model was 1988. We are into Mac revival so buying another drive doesn’t do it. Besides there’s a lot of legacy data in the disk.