How interesting !!
A tale of smoke and mirrors ..... On my N22, I have not heard this infamous creak emanating from the starboard forward bulkhead (where the mirror (acrylic, methinks) is affixed to). Then again, at my advanced age, I am sufficiently DEAF enough not to hear it. However, I am thankful that, upon gazing at my countenance in said looking glass, I see so zestful and vital a person who can still get away without the need for a make-up artist. I am one lucky and humble SOB.
But, seriously, folks ..... is it possible that the metal "thingamajig" that pierces the cabin roof and holds the bulkhead in place is, just possibly, responsible for this creak ??
Ernie A. in Toronto