Really Old American TV

[Brorat]

Way back in the 50s, there was a Saturday kid show in which a young high school student worked after school at a local store.  He would be sweeping up in the back room, when the window would open, and an invisible robot would enter the room through the window.  Once inside, the robot would be visible.

I know I didn't dream this program(me)!  I'm not that artistic!  Help.  What was the name of the show??

[Brorat]

I finally remembered the name of the show!  It was a puppet show that was a predecesor of Howdy Doody.  It was on in 1953-54, and was called "Johnny Jupiter".