Lava won't seperate or move

[Ace]

I just got this lamp, it was stored in my grannys stuff, and I think it hasn't been used in a while. When I heat it up, it just kinda sits at the bottom for a while. After a while, it moves up to the top in one blob, and stays there. What do I do to get the lava moving? Attached is a picture of the exact lava lamp, the pictures not too great but you can see the lava sitting at the top of the lamp.

[Aa]

Similar problem - I have a fairly new Lava Lamp that has been shaken around by the kids a little. The wax appears to have separated into 2 phases - one dense phase that has settled at the bottom - and a light phase that has risen to the top! I have tried heating the lamp to melt both phases and shaken it around to try and mix them - but to no avail. Anybody got any idaes what has happened and how to restore the lamp to its former beauty.. Aa

[Ace]

Yeah but now mine just sits as a big blob at the top, with a little bit of small parts of lava sinking and rising. Then it cools off after I turn it off, and falls back down to the bottom.