I have a lamp I'm experimenting with that has the liquid and lava from a Lava World 20 oz. blue/white made in 2008. That much is not an experiment. I know it worked in the original lamp before I cracked it open to rob the goo from it.
I've tried suspending the lamp above a tealight candle from 3.5" to 5". Above 3.75" the goo won't budge. Below that it cycles once or twice and then stays at the top.
I'm thinking I might have two problems. 1. The container isn't tall enough to dissipate the heat in the goo to allow it return to the bottom. 2. There might be too much goo in the container.