Here is a link to the Yahoo Janome Artistic group:
http://groups.yahoo.com/group/JanomeArtistic/
However, it has only 9 members and the last post there was 6 months ago. I would still recommend joining and posting your experience and question there.
Perhaps you need to contact Janome directly. I cannot believe a manufacturer would allow a machine like this not to have a working needle up/down feature. 18 months is not an old machine!