what size bulb are you using?
If its 100 watt, you will need to turn it down on the dimmer once it starts flowing or it will overheat.
I know it seems strange, but when they get too hot sometimes they won't flow.
As you are having the same trouble after 5 mins of turning it back on, I would assume it's getting too hot.
The bottle may be old as well, the bottle in mine is a little old and the wax doesn't flow quite how I would like it too, so i'm getting a new bottle for it.
try turning it down like I said above, and let me know how you get on, as I haven't had my lunar for long either.
Even if it's a 75 watt (as originally used) try dimming it anyway and see what happens.
hi federico, i know this has nothing to do with the flow of your lunar....... i have a lunar and to clean the metal work use silvo, its sold in most supermarkets and its in a tin(inside tin is like a cloth soaked in metal polish), you can use it on all shiny metal. looks great when done. let me know how you get on. x chris
Where the cable goes into the lamp looks like all of my lunars. The switch is not original.
The osram bulbs will work with the dimmer so your set. As i said let it warm up then lower the heat.
Mathmos sell lunar bulbs for over £9. I can buy the exact same bulb from the same manufacture for less than £1, same with astro bulbs. I think they rely on people thinking they are a special sort of bulb or something.
Enjoy it, they are great looking lamps with a very unique flow.