Ok, I managed to get a decent enough signal (35% to 45% strength)at the spot where it dropped to zero.
I read that the antenna should rise above the chassis, “at least 1cm” so it occurred to me that my tests with the laptop antenna were probably when it was hanging.
I decided to add a really thick buffer and that seem to have solved the problem. Moral of the story: get an external antenna.
My solution is ugly but functional.
