I had the same issue with one of my yellows. I refilled it and it flowed great for the first run, but then it started doing it again. I currently have no solution.
have you tried a different 40w bulb?
Whenever I personally have had this happen to me, it turned out to be a bare spot on the coil drawing water in. Maybe check to see if the coil is totally coated with wax? Sometimes you can't see the bare spots because they're too far into the globe, but usually they are right up against the glass.
I have fixed this problem on several globes by turning the globe in quick, short bursts to move the wax over onto the bare spot. Sometimes you have to repeat this over and over until it stays on the coil. Sometimes it never sticks again. That is when you have to pull the big guns out.
Not saying that is what your problem is, but check the coil out to be sure.
Yeah, mine does this also. Definitely a coil issue on mine. It wasn't on the coil all the way at first but it flowed good, then tried the spin method to reattached the wax to the coil but it backfired and now this is how it is. I plan to take the coil out and try the method Jus uses;
My yellow has the exact same issue. I just let mine go and it sometimes fixes itself. I gave up trying to fix these lamps. LOL
my green neon flowed like that for a short time, then it stopped. i have no idea why.