This baseboard heater (Hunter Heatmaster Convection Baseboard Heater - Model 35514) has come away from the wall. Its twin is having a similar problem.
It seems neither was installed using a drywall anchor or into a stud, so the screws slip out of the drywall rather easily.
I can't find a manual online (I think they're pretty old), and am trying to figure out how to get access to the installation screws in the back. I've tried some gentle nudging and pulling of various covers and panels, but nothing gives easy enough to be an obvious way in.