What I found is the half moons that hold the battery can keep the battery “offset” from the terminal.
You want to make sure the battery is centered long wise in the battery clamps and that the small sheet metal part that touches the end of the battery has sufficient tension to touch the battery.
The metal contacts bend very easy and do not have much “spring” tension.
You can remove the batteries, bend the contact inward slightly, but when reinstalling the batteries make sure you center the batteries in the clamps and not have the battery offset toward one side otherwise one of the terminals will not touch the battery.
Hard to explain in words, pictures or a video would be much more explanatory.