Yes there was a KOMO FM at 98.9 on your FM dial. It was featured in an RCA publication as a Salute to KOMO for installing lots of state of the art RCA equipment. You can view a PDF of the issue on the americanradiohistory.com website where I have lost many hours browsing all there is to see on that site. Here is a link to that RCA Broadcast News, dated October, 1948. When you read the article you will see the FM transmitter in the street level floor plan on page 11, the FM transmitter can be seen on page 17 in the back ground of the KOMO-control room. The transmitter can also be seen on page 38 and 39 mention in Fig 9. So read about the KOMO studios and KOMO FM.
And if that was not enough to the left you see a publication from September 1, 1950 with a picture of the KOMO FM tower at 4th AVE. http://nwradiohistory.com/wp-content/pdf/komo/Electronic_world_sept_1_50.pdf
Here is an application for KOMO FM to move to Queen Anne hill.