The Logitech Internet Navigator keyboard is a fairly nice keyboard with a decent enough feel for a membrane keyboard. Usefully it is liberally studded with several more customisable buttons and a scroll wheel. The latter is very handy for scrolling down webpages. My main OS is Linux and by means of a support daemon like LinEAK (there are others) it is possible to configure those additional keys. If you have X configured for 5 mouse buttons like so for my Microsoft mouse:-

        Option      "Protocol" "IMPS/2"
        Option      "Device" "/dev/psaux"
        Option      "Buttons" "5"
        Option      "ZAxisMapping" "4 5"
        Option      "Emulate3Buttons" "no"
        

then the scroll wheel works automagically.

This is what the keyboard looks like. The labels are mine and remind me what I've set the keys to do ;-)

The 4 LED's (in the black bit at the top, underneath the volume-down button) are, from left to right, F-Lock, NumLock, CapsLock and ScrollLock. All are a standard green ; the F-Lock is a Logitech "innovation" and switches the function keys between function mode and Logitech mode.

This is the my only gripe with the keyboard - why add another layer of functionality onto a set of keys which are supposed to be user-definable in the first place?! I understand why Logitech has done this ... I happen to disagree with their reasons! Annoyingly F-Lock is often not held on at startup so the function keys don't work. My KVM switch sometimes holds the key state and it appears LinEAK does as well (not sure if this is by design!)

My wish was to replace the F-Lock LED with a blue LED - since F-Lock is an "unusual" function I felt I had to replace it with an equally unusual colour ;-)
CapsLock was going to be orange which I felt would serve as a nice warning LED.

Turning the keyboard over, we find that only two of the 10 screws need to be removed to lift off the upper button panel:-

This already gives sufficient clearance to detach the flexible ribbon and lift the top button panel away. I didn't do that at the time because I was unsure whether the ribbon detached horizontally or vertically and I wanted a closer look.
Here's what the keyboard looks like with its covers removed:-

The LEDs are mounted very close to the board ; a plastic light-guide (an extruded piece of plastic with a channel per LED) serves to present a diffuse light source at the top of the keyboard. To stop light spilling over from one LED to the other a black cover is also included.

Here's a close-up of the PCB underneath the panel and connection:-

On the right we see the keyboard lead connection ; the shield-ground is brought out to a spade connector which loops around a smaller screw on the PCB.

Underneath the right-most LED it is possible to see the silkscreen for the circuit ; the LED Anode (+ve) is right, the Cathode (-ve) on the left. Since LEDs are polarised this is useful in mounting the replacement in the correct direction.

The ribbon cable has a stiffened end which plugs into the socket. It may be removed by holding it gently but firmly and pulling out from the socket like so:-

and so:-

Marking the cable and socket at one end with indelible ink will clarify cable orientation!

I found it easiest to manipulate the PCB by removing all ribbon cables. A pair of "helping hands" to hold the PCB did a splendid job of letting me remove the solder on the existing LEDs.

Here's the PCB prior to modification:-

To ensure the correct component is removed, I tend to mark the underside of the PCB (or whatever side I'll be working on) like so:-

Remember that most LEDs are rated for no more than 10 seconds of heat on the leads. Excess heat will cause the P-N junction to separate, resulting in a dimmer LED and - eventually - in a broken semiconductor.
Removing the solder should be performed as follows:-

• Cock the solder-sucker and hold it in one hand ; the other holds the (hot!) iron
• Apply the tip of the iron to the solder joint until it melts ....
• ... quickly bring the tip of the solder-sucker in close and press the release stud to suck up the liquid solder
• You may wish to apply a flexible heat-sink to the lead now to help the device cool..

If done correctly most of the solder should be gone and the lead should be pretty loose. If solder remains let the device cool for 30 seconds or so and try again. I typically use the interval to de-solder another component to improve throughput ;-)

Note the traces around the leads will typically be very thin - if you've bridged some traces, let the area cool, then re-heat the spillage and suck it up. Often capillary action will draw solder "blobs" together so the hot tip of the iron may be used to "clear" a path after most of the solder has been sucked up. In tricky cases, desoldering braid (a braided copper flex with flux which uses capillary action to draw solder away) may be required to clean an area.

Here's what the PCB looked like after I'd replaced the two LEDs:-

Being the cautious type, I re-assembled the keyboard PCB by re-attaching the ribbon cable and then plugged it into a spare port on my KVM without screwing everything together. Since the KVM is powered it provides +5V to the keyboard and allowed me to test it. A fault would have been less tedious to rectify this way.

After putting it all together, this is what it looked like:-

The blue LED in particular was a tad brighter than I'd anticipated. There was a certain amount of light overspill ;-)