Up for sale here is this large vintage Oak push switch. This pushes in but is a temporary switch, so it pushes back out when you let go of it. I am guessing it goes to a tube tester but I don't know for sure. This is guaranteed to work for you. Please see my pictures for details.

US shipping and handling is $5, and international is $18. If you have any questions, please ask.

I have more switches and other vintage electronics listed--feel free to take a look!