Well I didnt do the sudsy water method to see if I could locate the leak. As stated above, I squirted weatherproof silicone in the groves under the corner marker. So if anyone interested what I did (not pretty if you remove the light):
#1 unscrew and remove corner light
#2 dry out the area and clean well - I dug out leaves, sticks, bugs, etc and blew it out out with an air compressor
#3 pull out grommet. Mine came out easy as it was dried up from age
#4 blow out area again and make sure it is dry and clean
#5 squirt some silicone around the hole and on the underside of the grommet and push back in hole
#6 squirt silicone on top of grommet and press it into the top of the grommet
----I did this initially thinking it was good enough but it wasnt - water came instill somehow
#7 put light back and screw back into place
#8 look at the front and back of the light and in the track you will see the track leads to holes (tunnels) under the light. I squirted silicone in the 3 tunnels plugging them up

To get the little stains out of the headliner - I will take Dryel pen and remove them
https://www.amazon.com/Magellans-010...AQ5R378JY1JY0E


NOTE:
Went driving in the really hard rain. By filling up the tracks (tunnels) and sitting at a redlight, I noticed that I had a stream of water come down the front outside part of window - like 3 inches from the driver side frame. Not really problem for me because the wipers wiped it away and there is no leak on the inside