My fix costs virtually nothing, it takes 30 mins or so to find something to use to do it and hardly any time to fix it. Use super strength double sided tape on the back of the iMac and let it rest on the stand. Rock solid!
"After reading all of the woes and how it needs to go away for repair, be prised apart and sometimes comes back mis-aligned I thought I would make a fix of my own. It took me two goes while I understood the forces acting on the stand and iMac due to the angles, but when I figured out what to do it took me around 20 minutes.
If you look at the back you will see the cooling slots that you do not want to cover, and the RAM cover which is weaker than the rest of the back. I looked aroung my garage and found a couple of bits from some bathroom fittings and a bumper fom the front of a metal desk. I pushed the metal bathroom fixing inside the hollow end of the desk bumper and placed it on the metal below the cooling grid, then when the weight of the iMac tries to push itself down to the bottom my improvised bumper stops it at the perfect angle for me. I applied double sided tape to the part touching the iMac to keep it from moving and it is now working as a correct height bumper, invisible unless you look for it.
Now, if my iMac develops a real problem that needs internal work I can get the stand fixed at the same time, if not (hopefully) I will live with it as it is. I can't tell any difference now. You will also be able to do this, maybe with a rubber door stop and something stuck onto the back below the grille, trial and error until you get the right angle. It's so much better than sending it away to be prised apart!
