The elevator is missing the fourth floor button.
You should find a replacement button for it. What other things have buttons?
In the office at the first floor. Click on the coat rack.
The button like that won't do much. It is not conductive.
It is made of plastic. Metal would be more conductive. ?
Check out the science fiction section at second floor
Take a metal strip out of the rocket in science fiction section on the second floor.
Combine it with the button to make a conductive button.
You would need help from someone. Advance other things to meet that person.
Read the microfilms.
Good. Have you met someone good with wiring houses etc?
The ghost of Gail Plinkman is present in the hobby section at third floor. Give the conductive button to Gail. The elevator is now fixed.