Memory door on 27-inch iMac 2017

Make sure you first move the memory carrier back into place and both latches are locked in place. If this is not done, then the memory cover won't fit.

As for the memory cover itself, it will require a little bit of pressure to push it into place. You may need to start with one side, then the middle, then the other side. Remember what it took to pull the cover off even after the cover was released & pushed out? It will require a bit more effort to reattach it.

peterpatter wrote:

The cover has many tiny springs around its edges. If two or three of these are damaged (possibly when the original memory modules were installed), the cover can't be pressed in all round, to get it flush with the surrounding surface. The top edge (just below the vent slots) sticks out about 1mm, and will not press in further.

It seems wrong to press it in with force. Because of this situation, I have put a strip of masking tape over the top edge to help seal the cover. Perhaps I should remove any damaged tiny springs from the edges of the cover, and then re-insert it. Before I do this, what do you think? Feedback please.

I would not remove any bent tabs because you will likely cause more damage and have sharp edges. I would gently bend them back so that they just miss making contact when inserting the cover, but not so much that they bend inward to touch anything else (or snap off).

Keep in mind the tabs are meant to stick out a bit because they are spring metal & need to be able to apply pressure to the iMac frame to hold the cover in place. You only want to deal with the tabs which are completely blocking things and avoid touching the others. It is very easy to make things worse or where the cover won't fit snugly.

Check the exact recommendations here: Install memory in an iMac - Apple Support

For example, one model says:

"Replace the memory compartment door. You don't need to press the compartment door release button when replacing the compartment door."