How does one open the 3 pin Jones plug?

[jeffinmn]

I picked up some used Jones plugs. They are the 3 pin type used to connect a wall box to the mid 1950s Seeburg Jukeboxes. I've used these in the past and find them difficult to open. I know you have to unscrew the pin thaat holds the cover on. The ones I got I'm really struggling with and can't get the pin out. Is there an easy way to do this? 

[jukeboxmarty]

Try a pin punch.

[Ron Rich]

The answer to every problem of this nature is simple--Di-no-mite ! Works every time---
That's not a screw--it is a pin with threads--sorta-- I use an old pair of wire cutters--get it under the pin head twist and pull at the same time.