Not "pulling"? As in not heating the coil when firing?
If that's the case, the center (positive) pin in the battery may have gotten pushed in a bit from over-tightening the topper. Happens. Our "training" is that electrical connections should be tight. In vape-land, snug is the goal.
But if that's it, probably an easy fix. Turn the battery off - typically 5 clicks. Then, using a straightened paper clip, tiny screwdriver, or similar, "rock" the center pin gently from all around its side. You're looking to nudge that pin up just a tiny bit.
It's also possible - and from the same cause - that the mating pin in the topper has been pushed into the topper a bit. You can try pulling it out a TINY amount with small tweezers or, if the tank is empty and you can take the coil out, just pinch it at the base between the bottom pin and the bottom soft insulator.
And yes, backups are important! Good to have at least two of everything - including chargers
(And yes, B&Ms are generally more than on-line. Some of that's to be expected, as they have higher overhead. If they're reasonably close, I like to support my local business. The one you mentioned isn't!)