You might try dark drabber(equal parts drabber to color) and equal parts color to developer. Remember, if you want to repigmentize previously colored ends, always use a 5 volume mixed with the color mixture for only the last five minutes of processing time. OR, apply equal parts color to developer to the gray roots and process 40 minutes. then take the remaining color/developer mixture and dilute that by half with distilled water and apply to the previously colored ends.