From the pic the gumball seems to have one of those button photocontrols installed on a JB cover plate.
As I suggestion, I'd say you could install a JB coverplate with a standard 3/8" knockout and find a way to install a twist-lock socket. Or if you have access to a drill, drill some holes into a plain JB coverplate and install one of those twist-lock receptacles.
Yep it has a button PC on the JB above it, it would be cheapest to just replace the current PC with the same type and since this is a not for profit organization that would be the most affordable cost. And of course I have access to a drill, I have my own cordless drill the I got back in July and I also have an older corded hammer drill.
As I suggestion, I'd say you could install a JB coverplate with a standard 3/8" knockout and find a way to install a twist-lock socket. Or if you have access to a drill, drill some holes into a plain JB coverplate and install one of those twist-lock receptacles.