For Chinese manufactured products I shop customer service rather than brands. I have 3 SLB Twists and 1 regular-sized Vivi Nova from vapor beast. All work perfectly and one of the Twists survived, no worse for the wear, after landing on a hardwood floor when I tripped and slung the poor thing half way across the room. I ordered 3 Mini Novas for myself and one for my daughter from Vapor Kings. I also ordered 2 Joye Twists from them for my daughter because Vapor Beast was out of Twists when I needed to buy them for her birthday. Those are all working perfectly as well.
If pulling the posts up a bit doesn't solve your problem I would suspect something odd going on with the Vivi Novas.
If pulling the posts up a bit doesn't solve your problem I would suspect something odd going on with the Vivi Novas.