If you've lost the manual for your Medalist Dart Star 2000 Dartboard, there's no need to worry, as there are several sites online you can get a copy or get help regarding finding a copy of the manual. For example, you can download a copy from dartliga.dk/wp-content/uploads.
Another site, arcarc.xmission.com/...Darts, also offers a PDF of the manual.
You can also download Medalist's repair guide for the Dart Star 2000 at home.comcast.ne. This is a Dutch site; electronic darts is very popular in the Netherlands, but the site is in English.
A forum for arcade enthusiasts, forums.arcade-museum.com, has a thread about repairs to the Dart Star 2000 machines. Perhaps you could look in on the forum, or even join up and ask around for a manual?
Finally, you can try Medalist themselves on their helpline (253) 939-2900, or you can contact their service department via email here.
This promotional YouTube video has more on the makers of the Dart Star 2000, in the information field above the comments section: