If the tuner has failed, consider an HD capable set-top tuner. This assumes you have at least one unused HDMI port free.
http://forum.tvfool.com/showthread.php?t=2882
However, your inability to receive KOMO reliably with the RCA TV leads me to conclude the surrounding vegetation and/or buildings and terrain are going to force you to consider a larger antenna.
Until a year ago, I lived in the north end of Seattle. An Antennas Direct 91XG and Antennacraft Y5713 were not overkill due to conditions common to the Seattle area. My old TVFR looked better than yours on paper.
A Winegard HD7694P or Antennacraft HBU-44 would also be worth your consideration.