Surely it's OK to Bump a thread .... it's a common practice on most forums I've visited. A forum is dynamic with users joining all the time with their own personal wealth of knowledge, and existing members may have missed it first time round. I recently bumped a thread on a silver specialist forum, almost a year after the original, and someone came up trumps identifying the design. It's maybe not very welcoming to tell people to take a hike?
