What is the Magic Key Snap-on?

[Scorpion8]

One of the key caps on my X220i (left CTRL) popped off when I was pushing on the keyboard to remove it. What's the magic method of re-attaching the key-cap? Just pressing down firmly doesn't do it. Do those two small tabs along the top go into the holes on they key hinge thing?

[theterminator93]

There's some method to the madness.

Depending how the key came off, you need to take a variety of steps to reattach it properly.

The base of the keyboard has some metal attachment points. This varies between keyboard manufacturers and model, but in general, there are "O" shaped holes and/or "L" shaped slots that the stamped aluminum has cut out, and bent up. There are little plastic tabs on the key scissors mechanism that go into these, and the same on the back of the key, which hold the key on both ways.

Then there's a plastic scissors mechanism. The two pieces usually attach to each other at the midpoint. If they have separated, check to be sure one of the pieces' isn't missing one (or both) of the small plastic pins that go into the corresponding holes in the other piece, then reassemble them carefully by inserting one tab and squishing/flexing slightly to fit the other tab in. You may need to test fit the pieces together to ensure they are in the right orientation, as they should fit together and lay completely flat/inside one another.

The scissors mechanism goes on one way - there is a side that faces up (away from the keyboard base), and there is a top (that points towards the LCD). Usually this is fairly evident because you will see that the small tabs/attachment points of the keyboard base will line up with the corresponding tabs on the scissors mechanism. The scissors mechanism will also need to be able to "X" away from the keyboard base - not towards it - so that will help you orient it properly too. There is usually a short pin/nub at one end that you can slide into one of the "L" shaped slots on the base, then you squeeze/snap in the pin at the other end into the "O" shaped slot on the base by flexing the plastic slightly. A small flat-tipped screwdriver to wedge it in helps here.

Once the scissors mechanism is attached to the keyboard, you will see a similar "L" shaped slot on the underside of the key, as well as couple small "C" shaped snaps (usually - again, depends on keyboard model). The idea here is to lay the key onto the scissors mechanism so that the "L" slot is adjacent to the pins that fit into it on the scissors mechanism. Then slide the key so that the pins go into the slot. Once that's done, push down to snap the other pin on the scissors into the "C" snaps on the key. The generalization here is the "L" shaped slot has to be lined up first; this will always involve lining it up, sliding the key so the pin on the scissors slides into the slot - THEN pushing down to snap the "C" clips onto the other end of the scissors.

This is a long-winded generalization but if you can understand that, it should give you the gist of what's going on. A few pictures or a video would help a lot more. I am sure you can find something on YouTube if you need it.