Kevin

Regarding the 2013 27" iMac, and it leaning forward as if it's been in captivity too long... I have swapped the hinge mechanism on several 27" iMacs, all 2013. Not to be confused with earlier models where you can insert a credit card in the back to release the mechanism or any modified Vesa mount, the above models were just factory standard. The issue is a really poor design, where 2 high tension metal springs are held in place by 2 plastic couplers. The cheap plastic couplers (if that's the correct term), eventually break, and the screen leans forward. Many users report hearing a loud crack when it breaks. You can't adjust anything here. You can't tighten ANYTHING to fix it. The temporary fix is to wedge some foam between the back of the display and the screen. You have to purchase a new hinge assembly (see photo), it has the same cheap plastic couplers while the whole assembly is metal. I was unable to find just the couplers on their own, but a little imagination or a few episodes of MacGyver might help...