I also have no-side plug Halos, and the box is neatly closed. It looks like I hit the Mono-Stereo slider pretty hard once, but I still get good stereo sound. It's worked great the last 4+ years. Once you start using it, you'll love it; if not, return it for a refund.
Once I thought I was having problems, the right side hardly had any sound. Removed earplug to check, the tube was about to come off. Pushed it back onto the little barb, it's been working fine ever since.
Post a follow up with how they work for you.
After a few times, putting them in gets easier, but the first few times it pays to reach over your head and pull the ear up while sliding the plug in. Right hand pulls left ear up while left hands pushes plug in. In time, it becomes a one-handed process.