Just my 2 cents:
I think you have to consider the purpose of this forum. Generally speaking, in my view, it is here for tournament directors. That may or may not be true, but before becoming a TD, I didn’t even know it existed.
As a new TD, I asked a lot of questions, which drove some forum activity, and then, once answered, the activity stopped. I am certainly not an expert now, but all my questions about our smallish events have been answered, so I don’t ask any more questions, and then my forum activity dropped accordingly.
That said, when other new users jump on the forum, I have tried to help them with my limited knowledge, only to have more experienced TDs override what I said, even on opinion based information. So, now I don’t answer anyone else, because I am afraid of my answer being wrong or unpopular. And thus my participation has dropped. I even debated for the past two days if I should respond to this thread at all.
If the forum is just for TDs, I might note that none of the 6 TDs in Alaska, other than me, use this forum at all. Why is that? Lack of advertisement of its existence? Lack if perceived usefulness? I don’t know. When I became a TD I needed this forum, because I had no TD to study under (at the time, I was the only TD in Alaska). I’ve mentioned the forum to them, but I don’t see them here in the forum. Perhaps they don’t need it because they watched my events?
If this forum is for general members, none of the membership in Alaska is on this forum, except me. While that is only about 110 people, that means that less than 1% of members in Alaska use it or know about it.
But, on a positive note, in general, I would say if you want more participation, post interesting topics to discuss and maintain an open and friendly atmosphere while advertising the forums availability. 
