Hmmmm I can't find it in my files, but I'm pretty sure that if you mouse-click on the periscope you currently have, in the eyepiece or around it, it will take you to the bigger periscope screen.

Doesn't that work for you?
I think I remember now that it was the "lite" free version which had the normal periscope, but I do not have it and have no idea if it is still hosted somewhere.