Fester that's the new plug in the update kit. It replaces the old one that was having some issues with moisture. There should be another one separating and feed the tachometer depending on the age of the update kit install. Your problem is most likely up in the ignition switch which is why wiggling the harness gets you a connection. You have two choices along with the EB kit one will be replace the ignition switch the other would be key-less. Either way since your is a classic the EB kit should be done.
If you go the route of a new ignition switch you can just change out the bottom so you retain the same key as the rest of the bike. The new switch will come with the same matching plug as long as you order it for a newer model like the 09 model. Stay away from the Roadster switch as it might have other wiring in it for the gear indicator and ABS stuff. Also even if you change the ignition switch out you can still go key-less if you want.
Hope this helps
