Thank you sir. I will try these things!

Clark Jester said:

I agree.  This column can be cool but not always.  If I were you, before tinkering with the "solution," I'd honestly take it to another room.  Upstairs, downstairs, in the celler, in the garage.  Get it going there.  See what happens.  You could always leave it on and then turn it off and then turn it on to "shake" things up.  Lava lamps do funny things.  Sometimes it the pressure outside.  kind of like when it's the best time to fish.  Good Luck.

there's another trick, if the above ideas don't play (though I reckon they've covered it, it does sound/look like a heat issue)

I'm no good at MF mix adjustment, so have learnt to play with bulbs and dimmers...you could fit an inline dimmer with a slightly more powerful bulb and experiment with fine-tuning

the UK Crestworth/Mathmos Lunars - pretty similar in size to your Grandes - came with a good quality Relco inline dimmer, (don't know about the new IOs), and it is a crucial part of the lamp's operation

Jezza said:

When I hear "shake it up". Fear goes down my entire body. You mustn't say things like that on a lava lamp website. Its like running long nails down a old style blackboard. 

If anyone shook one of my lava lamps I'd kill em. 

Only joking. Enjoy your lamps!