For me personally you may not want to advertise that you will merit the members or promise it. In the past this tends to attract members not looking to be useful but that are just seeing the chance to get that coveted merit so they can wear a Sig again.
If you simply post your thread and bump it daily, there is a good chance you might find a useful member to engage in the subject because they want to, not simply for the merit.
Mods would better serve that board from what I understand. However if you are active there, surely you can think of an established member you could try and convince to become a source. You yourself could spend some time looking for "quality" posts deserving of merit and apply to be a source, no harm in trying. theymos has made sources for local boards with as few as 10 smerits a month I believe.
More to the quote though if people aren't contributing there solely because a lack of merit sources, then they weren't really contributing anyway. I can understand leaving due to lack of moderation as it can be trying to sift through trash for a decent discussion or relevant knowledge.