Etherwave Plus loose wire

Hallo.
I’ve just acquired an Etherwave Plus and this evening I removed the top cover.
There is a black wire running from a connector in the middle of the switch panel - where should it be connected to? At the moment  it’s just laying loose!

Sometimes the black wire that is terminated with a solder lug is one that should be screwed to the aluminum foil patch on the pitch side of the main board.  If you see a screw hole in the corner of the patch with no wire then this is probably it.  It's a tuning thing, and sometimes a user will disconnect it.  Mine is disconnected.

If it's a different black wire, try posting a picture.