Lunar issue

[IdOrU 02]

A year ago, I bought a clear/white lunar replacement bottle from Mathmos and a clear/orange one.
I got them flowing kinda ten times during the year passing by. They were showing some odd behavior but I got along with it. (I have a total of four bottles, these two with two old: blue/green and clear/red).

2 days ago, I turned them on. The clear/white started its spikes then melted down, leaving all around the bottle some residue, like the wax was attached to the bottle. The wax finally succedeed in flowing but only by the bottle side, growing all to the top with a tiny blob. I let it run for 5 hours, trying to tweak the temperature with the controler but the lamp failed to flow like it should. I ran it again today, the wax still sticks to the bottle, the blob only growing by the side of the bottle.

The clear/orange displayed this behavior only once to finally normally flow. It is strange how these 2 bottles, pretty new, act so badly (at last for the white now) compared to the old ones that flow very well, without any bubbles.

Does somebody have a clue to what happen and how to fix it?

(I tried to very slowly and gently rotate the lamp when it's half cooled down, but that didn't do it).

[IdOrU 02]

in fact, the wax is sticking to the bottle, all around or almost and for approximatively the topmost two third of the cold wax hight. I'll be doing some photos today and post them to show the issue.