I am always of the frame of mind that customer should not have to fiddle with things to get them to work. That being said, I also know from first hand experience that most folks would rather gamble with a fix, then have to wait on replacement equipment.
So let's address you Diamond XL Battery, the reason it is not charging could be 2-fold. One would be because the charger has an issue. When you plug the charger into the wall socket does the LED light come on and is it red? If it does come and show a red light we can eliminate that. The second would be because the battery needs an extra 1/4 of a turn when you connect it to the wall charger. The threads on the Diamonds are just a hair taller then the standards keeping them from making a solid connection with the charger post.
Intermittent performance with Passthroughs can mean 1 of 3 things, the post isn't high enough, there is a loose wire, or there is an issue with USB source. Let's cross out the USB source since you are using a wall wart, let's say that the PT cord has never been stretched or accidently had a car door closed on it in the past, which leaves us with the post needing to be raised.
Now I know you said you attempted this earlier, let's revisit it one more time, the post should be high enough so that when you go to screw the carto onto it, you can feel that there is a good connection and the there is a gap between the battery connector base and the carto connector base as shown in the video.
If you are willing to give both of these fixes a try and they still do not work, contact C.S. for replacements.