Quoted from Industen:Close the coin door when you do the test.
No need to close the door. There are two switches that the coin door pushes closed, one of them is dented all the way around the top (see pic) - pull this one out and it closes the switch as if the door were closed, allowing for the solenoid and flasher tests. Bam! I learned this watching Ray's Tech Tips by GRC on YouTube. I learn something each episode, highly recommended!