Over time, many of the available three-character special event call signs in the U.S. will make their way into the ADIF log kept by WSJT-X. This may make you think you've already worked a special event station when actually you worked it in a different context. Examples are 13 Colonies in a previous year or when the call sign in question was assigned to a different event.
Use File, then Open log directory. Open the file wsjtx_log.adi with a text editor and replace all occurrences of "<call:3>" with "<call:6>000". This reversible change will prepend 000 to every special event call sign in WSJT-X's log, thereby tricking it into thinking that those QSOs never happened. Not a bad idea to save a copy of wsjtx_log.adi before you mess with it.
