There is a problem with step 10 of this guide for 27” iMac 5K Display 2019! If you follow step 10 as it is, the iMac microphone port is blocked with adhesive. After following this guide I had to buy an extra set of adhesive strips and reopen my iMac to fix the muffled microphone problem! The correct application of the adhesives in step 10 is described in iMac Intel 21.5" Retina 4K Display (2017) Adhesive Strips Replacement guide iMac Intel 21.5" 4K Retina-scherm (2017) Vervanging van de kleefstrips

Please do update this guide accordingly!