stuck key: for standard rubber dome keyboards, keyboard past warranty and has special keys you don't use (internet, email, wake, power):
the rubber domes for the special keys typically are stiffer. they are also usually used less. if you are replaceing a highly-used key like Enter, backspace, and spacebar, or F5, these are good candidates for replacing the rubber dome, especially the spacebar.
fix in a nutshell: replace existing spacebar rubber dome with a stronger one. this mitigates the wear problems and provides extra spring in the spacebar which I like (because I have a "heavy thumb"). replacing with a stronger one seems to give the needed extra spring.
for me, the problem wasn't due to garbage in the keyboard. it's due to plain old wear because it was a $5 keyboard and I had it for 6mo-1year. pay $22 for a 20,000,000-keypress keyboard and it will probably last 5 years.
you should know that the rubber domes may come in different clear-silicone colors depending on strength: maybe clear for lowest spring, green for mid-strength spring on Enter backspace space, blue for high-strength spring which would be on the special keys.
- canned air duster $5/can
- small philips head screwdriver (don't know the #)
- LED 3W (200 Lumens) flashlight
- Blue Shower tech cleaner/degreaser (optional) $18/can, available from newark.com, mouser.com or digikey.com under chemicals
- rubber gloves or nirile exam gloves you find in bulk at walmart.com for the Blue Shower
- tweezer-dexterity ability - ability to do fine/small work with fingers or tools
- shutdown computer. this does not really turn off power to the keyboard or motherboard. there is still power as evidenced by the green light on your motherboard.
- unplug computer or turn off power switch on back of power supply if it has one to make absolutely sure the power is really off.
- unplug keyboard.
- take keyboard outside and canned air duster and blow out every bit of debris
- take keyboard inside, place keys-side-down on clean highly-contrast surface, like wood or wood-colored formica or a dark wood table.
- move the cable out of the way. you don't want it getting near the rubber domes due to scatter factor or on anything that makes up the insides because of the metal connector possibly scraping something it shouldn't.
- unscrew the screws except for the screws that hold down the smal circuit board with the LED's on it. the board with the LED's on it have a pressure-connection to the keyboard wiring matrix, and there's usually nothing to clean there. lay out the screws so that they are in the order specified by the holes, some keyboards have different screws. keep this layout away from the keyboard about 1ft so as not to scatter them.
- CAREFULLY lift off the backplate VERTICALLY
- replace any rubber domes that have gone missing in the process: clear ones can be really hard to see. a flashlight may come in handy for this. look around. DO NOT BLOW ON THE RUBBER DOMES WHILE SEATED - this will blast/scatter the teeny light rubber domes in every direction. resist the urge. better to remove individuals and process them each separately away from the keyboard (blow or rub to get debris off).
- clean the keyboard wiring matrix plastic sheets: carefully lift the clear plastic layers on the backplate that have the aluminum or tin circuit traces (the keyboard wiring matrix) and clean debris and oils, liquid spills, etc. out with your hands and rub your hands over the garbage can. you canb blow probably shouldn't use chemicals except for maybe blue shower (it's a tech cleaner/degreaser) it dries fast, but stinks and it's not good to breathe or get on your hands, so use with some windows open.
- IF you have special keys on a multimedia keyboard or other non-standard keyboard with keys like internet, email, web, etc or some other key that you can sacrifice, and these keys may have a stronger rubber dome (on the keyboard I worked on these spring strength levels are indicated by the color of the rubber dome). swap the bad key (spacebar, Enter, backspace, F5?) rubber dome with the stronger rubber dome. do this for all needed keys to replace. I like to whack my enter key, so I would need a stronger Enter. this should fix the problem of the key being stuck down sometimes for awhile at least. it depends on the quality of the keyboard design. cheapo keyboards can't expect much, but this may expend their life if you don't happen to have the $5 keyboard+$5gasoline to get a new one.
- hold the backplate backside up, using your fingers to hold onto the plastic keyboard matrix layers. CAREFULLY CAREFULLY and parallel to the rest of the upside-down keyboard let it down. be precise. if necessary to get accuracy on placement, put bottom edge of the keyboard in place at 2-5 degree angle and get it parallel, holding on to the layers as long as possible so they don't slip and run away dragging rubber domes with it (and this having to start over from scratch).
- before putting in the screws, make sure it got in OK by checking for too much uneven placement. do not lift it up to avoid starting over maybe.
- screw in the screws using correct placement (the layout you put them in earlier).
- plug into computer or turn on power supply switch
- turn on computer (power button on front).
- fire up notepad. [windows-logo-flag-key]-R notepad [Enter] or start, accessories, notepad
- test each key including [alt], [ctrl], [windows-logo-flag-key], [context menu], etc.
- if anything doesn't work, try again or recycle the keyboard.