Lesson Learned: I finally found the source of leaks in my windows - the old security sensors
During heavy rains my windows would leak from the 2nd floor down to the windows below it on the 1st floor and drip/stream into the house. We had flashing replaced and a few people come out to fix it, nothing did the trick.
Well, it turns out that during the house's construction in the 90s the original homeowner had a security system installed which required a hole to be drilled through the bottom of the window frame (a few inches from the weep hole drain), through the sill plate/window frame, and then a sensor could be push-fit into it and wired up to the system. They never sealed it. Not a single one was sealed in the entire house. Once I realized this, the damage/warping below each window now magically correlated to each sensor hole location on the widow a few feet above it and I had the most "DOH!" moment of my home ownership career.
I had only overlooked it because I had no idea there was a sensor there in the first place and the sensor plug just looked like it was part of the window. During routine cleaning I saw one of the sensors had popped out every so slightly and right then I knew. I caulked each sensor plug, and we're now dry as can be.
Wasn't the first, and won't be the last lesson learned! It's really hard to see the most obvious things sometimes.