I would increase the heat as a last resort, because if you do that it might permanently ruin it. This seems to be fully melted, and flowing beautifully! I would just let it run multiple times and see if it starts to separate. Also, I would check to see if the lamp is sitting in a drafty area that is not letting it get quite hot enough.
is the lamp sitting near or under an air vent? if so, that may be the problem.
My son's china 52 oz is temperamental like that!!! If he has his window open and it gets chilly in his room, his sometimes will look like that, but it's still not even fully melted!! I would probably go out on a limb and say the room is too cold for that particular lamp. Also, as pointed out, by Kim at Magma Tower's after a lengthy conversation, the aluminum bases let a ton of heat to escape. Now factor in, the pinholes or moon and star cutouts in the Wiz's and it could make for a fussy lamp when it comes to temperature differences. If you do decide to go with a 60 on this, a dimmer is an absolute must. This is what I use. You can get them cheaper. Shop around.
Now goo kits are a horse of a different color. Most of the newer goo will not run on a 40. I know there are members who have kitted years back and they can get flow just fine on 40's, but I think they may have changed the goo. I still can't seem to find the answer on this question as to why some can get flow on a 40 and some not. I do have one kit that I can get flow on a 40 but it takes like 6 hours. I use 60's on all my kits and dial them down about 1/4 of the way if the room is chilly. If the room is hot then it's closer to 1/2 way. I adjust accordingly because the ambient temp in the room messes with the kits pretty good. I use these and you can get the 2 pack pretty cheap at walmart or kmart. I even get them from the supermarket I work at.
I think it looks great as it is, but that just a matter of option I guess. Has the lamp run much? could just need more time to break in and I wouldn't suggest running a 60w, they'll eventually fry out your wax, and I'd hate to see that happen to a American globe.
I have a clear/purple 52z USA globe that did the same thing I ran for 8 hours at a time over and over again but I could never get it to flow. Now the wax just sits on the bottom and shots up little balls. I have herd that some of that some of the 2002 USA lamps have quality issues but I don't know what the date of your lamp is. I would try running the lamp 8 hours on and 8 hours off for a week this has worked for me in the past. Good luck!