Cleaning lower manual key contacts

The key contacts where in very bad condition.

First I cleaned the springs and bus bars with isopropylalcohol and a wadding rod. The wadding rod turned grey, but that did not seem to do the trick.

The springs are gold coloured, the bus bars where silver coloured. Scratching the bus bar with a screw driver turned the colour into gold. So the busbars where oxidized.

Next I also had to scratch the springs.

Finally lowering the print with the contacts a little bit, in respect to the keys helped also.