What about adding a new heading in the help section, along the lines of resolved, success stories, happy customer, that would show resolved issues. Those seeking help could then look there to see if there is an answer to their question, The original posting could be left but then closed or locked with a notation that the topic has been moved to solved ,success or whatever the heading is named?
Anything moved there could be permanently locked. (into the sunset)
Another thought, or just put solved on the thread heading?