Checking and Preparing the surface below the Teak Deck

I spent some time today cleaning up the section of the deck below the teak that I removed.  I tap tested the area and it all seemed solid.  The strange thing is that it looks like this kind of work had been done before on this boat because while the teak deck was screwed down, I could tell they were not the original screws.  Also there were places where additional holes had been drilled and bunged.
But the biggest tell tale sign was that when I removed the teak that appears to be rotten, there was what looked like a thickened epoxy on the deck below the teak.  I am not sure if it was supposed to be an adhesive or not. If it was, it didn’t seem to do a good job of holding it down because there was no difficulty removing the teak at all.
Here is a time lapse video of the work I was doing.  I took time to vacuum a couple of times so that the junk didn’t go overboard into to the water.