Vintage Synth Repair

Interesting configuration. What are those semi-circles made of, and how are they affixed to the PCB? There's really no significant current flow here, so if you could somehow remove the contacts and then solder just a fine strand of a wire under it, then reinstall. Or if the pad material is solder-able, connect a very fine wire to the side of the pad. (Very fine soldering skills and a steady hand needed.)
---Kevin

gilwe@... wrote:

Hello friends.

Today I took my beloved Juno 106 out of storage to prepare it for a show. Checking the keyboard I found one dead key. I took the keyboard, key and rubber stripe off to see what's under it. What I found was that at the very point where the keyboard PCB trace for the certain key, meets one of the "half moon" contact, there was some kind of corrosion.

I checked the contact between the PCB trace and it's half moon, and found there was no contact between the two. That right-hand half moon is supposed to be connected to the same line with all other right-hand half moons of all other keys.

I'm afraid to try anything before I have your advice so I don't cause any further damage...

These PCB's are impossible to find.

How can I reconnect the track to the half moon and keep good contact between them ? I'm afraid soldering iron is not going to work here ?

Thanks very much for your advice !

Picture here:

http://i774.photobucket.com/albums/yy25/system100m/106_zps4f95c99c.jpg