Thanks for the advice. I have removed the windows and resealed it a year ago with butyl tape. Didn't use the Lexel caulk though. I did another window the same way, and it sealed fine. On this window though, it seems that the rubber/vinyl seals that hold the glass in the frame are coming loose at the bottom of the frame. I wonder if this is where the water is getting in. It seems to be a small amount of water but over time ruined the the wall panel replacement on the inside.
I didn't know if anyone here might have done a window glazing replacement or not. I saw a video that seems to make it look easy enough to do . . . assuming one has the right style.
When I reinstall the window,i will definitely follow your advice. Thanks again.