My brother in Australia has recently bought himself an Aladdin 23 (older English production). Without the gallery the flame is nice and even but with the gallery on it is a lot higher on one side. I guess there is a leak somewhere in the gallery to burner basket joint. Anyway, he has a super Aladdin burner as well so I was wondering if the gallery from that would work on the 23? That would get it working until the correct gallery got sorted.
I wonder if this is down to wick trimming - or worn cogs in the wick raising element. Sounds like too much air at one point. Something bent maybe? I have a Model 12 (circa 1928) and a 50's Model 23 of which the galleries are perfectly interchangeable. Don't know if this helps, but the Guild have a very good pdf on the Aladdin 12. http://www.lampguild.org/LIDigest/AladdinUK12_article.pdf
The wick is trimmed nicely and the wick winder works well. The cause is most likely an air leak but my brother hasn't investigated that yet. The 12 and SA galleries are identical (as far as I know), so if yours works on a 23 the my brothers should as well.
Are you checking this with the chimney in place? It often looks a bit uneven until you put the chimney on... Also they are very critical with regard to wick trimming, you have to use the proper tool to get the right profile. If you are certain the trimming is OK it could be the wick is catching slightly as it is wound up and down. If there is a leak, this usually causes flickering. You could try fitting a flicker ring anyway to see if that fixes it, but I have my doubts. Finally, yes the galleries can be swapped between the two.
The checking is being done remotely as I am trying to guide my brother on the other side of the world. I have used and collected Aladdin lamps for many years and have a number myself but my brother is a user, not a collector, and only has the one. I am quite certain the wick is trimmed correctly and when lit without the gallery the flame is even and stays that way when turned up and down. It is only when the gallery is put on (with mantle and chimney) that the flare on one side occurs. I have asked hime to turn the gallery to the three positions possible and see if the flare follows the gallery or stays put but I havn't heard yet. Maybe this coming weekend. As I mentioned before I was hoping he could use his spare SA gallery on the 23 burner to have it in working condition while he checks the 23 gallery. I was fairly certain and from what I have heard here, it seems you can swap the galleries. Thanks for that confirmation.
It might be worth checking that the flame spreader has no dents in it too... If it has then I've found you can very carefully straighten these with the help of an appropriately sized socket from a socket set.