Hi fellas,
To open the keyboard you need to remove the 4 obvious screws on the top panel as well as two screws bottom left (under the keyboard) holding the panel with the pitch and modulation wheels and one screw bottom right holding the narrow blank panel at the end of the keys. Once these are removed you can open the top.
To remove the keyboard and get to the contacts you will first need to carefully unsolder the red and white wires at the left end of the keyboard (you will need to re-solder later, white-front/red-rear) and clip the wire tie if present. Then unscrew the five screws at the bottom/front of the keyboard and three screws each on three angle clips at the back of the keyboard. Take your time and be careful not to strip or loose any of these screws, take note of where they come from so that you can return them to the proper place.
Once all the screws are removed carefully tip the keyboard up so that you can unplug the data cables. There is a lock clip on either side of each cable, simply swivel the clips out and the cable will be released. When you remove and replace the cables be careful not to bend the pins.
With all the screws, wires and cables removed you can lift the keyboard out of the case. Turn it upside down and you will see the contacts. There are two banks of contacts (thus the two cables). I removed mine and took them outside so that I could spray them liberally with WD40. I let them drip off the excess before putting it all back together.
I did this just today. The first three "f" keys were dead which I surmise was a result of dirty contact(s). Now they all work beautifully.
Take your time, make sure you have all the tools you need (just a Phillips driver and a good soldering gun, maybe some Nokorode flux and plenty of clear, clean working space.
Note; if you use a power driver be careful not to strip the screws. Start them in by hand to be sure you don't cross thread them.
Good luck!