toolbox149,
I think you may want to consider more thoroughly identifying the problem before proceeding to fix it. It could be some magnets, that are connected at various points on the stretched mylar panel, have loosened and clatter when driven hard.
I had tis with my 1st pair of Magnepan IIBs years ago. I didn't think of it as a tweeter issue, however, and noticed it more on the bass and midrange in my speakers. At higher volumes I noticed a clapping or clattering sound that was more like a vibration. After researching on the internet, I discovered this was a somewhat common issue that was caused by the glue that Magnepan used at that time failing. Magnepan had found a glue from 3M that remedied this issue. I decided to just buy a newer pair of used 2.7qrs rather than send them to Magnepan for regluing.
Your 1.6 or 1.7s are newer and it sounds like you'd rather have them repaired. So I'd suggest calling Magnepan to get their thoughts and a quote on repairs. I understand you're handy but it may be best to have them professionally repaired. I know boxing them up and shipping them to Minnesota is a pain but they may already have developed a better glue and process. Plus they'll likely give you a limited warranty on the repairs.
Hope this helped some,
Tim
