Atari 2600 Controller issue

Hello, I recently got an Atari 2600 Light sixer, But the player one controllers button triggers non-stop (like rapid fire) even when the controller is unplugged. I know a fair bit about electronics and have inspected and cleaned the console inside and out along with the controllers trying to remedy the problem. Any ideas?

you could have an issue with the console . there is a problem with electronics that happens over time where solder will grow tin whiskers and sort or bridge a gap or circuit . don't bother trying to see if you can see any of these as they are microscopic . nasa and the us military has had problems with tin whiskers before .it just happens something to do with the metal and an electrical charge. not sure if that is what you are experiencing but you may find it interesting . otherwise maybe look at the console again as somethings are not always obvious .