(mechically) stuck key

[cure]

It is a 600. Last night my 'u' key felt a little 'tight', but still worked, but this morning it is stuck in the up position. That is to say that it cannot be pressed down and a 'u' can in consequence be generated. It feels like that post that is presumably mounted on won't descend. This problem has happened spontaneously to three or four other keys in the last 3 months or so and has spontaneously cure itself. Strangely this often is a question of leaving it overnight or at least for a few hours. Physically moving the computer from place to place seems to be a factor. And since turning just now upside down the computer the spacebar does not seem very happy either (something that has come and gone also).

My questions are: 1) how do I manually unstick a key; 2) what is the mechical problem that is the cause of this?

Thanx for the assistance.

[cmarti]

Which model do you have?

As you mention it can be mechanical, but it also can be that it needs to be cleaned. Try to blow it with compresed air.

If that does not work the only option you will have to replace the keyboard.

You can find the cheap on ebay.

[cure]

Compressed air tidied things up but did not fix the problem.

[cmarti]

In that case the only option you have left is to replace the keyboard.

[cure]

Is the next logical step to remove the key cap and see whether something can be done to loosen the key?

[rkawakami]

Is the next logical step to remove the key cap and see whether something can be done to loosen the key?

My understanding is that there are a couple of manufacturers of 600 series keyboards. If yours is similar to mine, you can remove the keycaps with the following procedure:

Place a fingernail, preferably left index with the nail down, underneath the "bottom" of the keycap (i.e. edge nearest the front edge of the laptop)

With the right-hand index fingernail under the "top" edge of the keycap and with your right thumb positioned over the keycap, lift straight up with both fingernails at the same time.

With any luck, the keycap will come off (without flying away since your thumb is over it) and you won't break off the tiny clips holding the keycap to the two arms which surrounds the actual key switch.

I have a picture of what is under the space bar key here:

http://www.rkawakami.net/ibm_600x/images/space_key.jpg

In this case, there are two pairs of white arms on either side of the key switch (circled in red). For a regular key, those arms will be around the switch (which is why there is a hole). The arms have two pins in them with allow them to pivot and thus raise and lower the keycap. The key switch is covered with a rubber or latex dome and is what keeps the keycap in the "up" position. If there is anything which gets underneath the arms it will prevent the keycap from being pressed down. This may be your problem for the few keys which don't work anymore.

(edit: Forgot to mention how to re-attach the keycap: Simply center the keycap over the white arms and press down fairly firmly. You will hear a snap or click and that should tell you the cap is back on.)

[cure]

Thank for the excellent descripiton.

I was able to pop one side of the troubled key off, identify and remove the offending particule that was blocking it, and click the key back into place with an absolute minimum of effort.

I also learned that canned air blown from right to left or left to right is probably less effective than blown towards or preferably away from the screen. The key craddle alignment is the reason for this.