Bought a CDX2 from a well known auction site, cosmetically good but with known faults. It played but the majority of the panel didn't function.

Got the cap kit from Martin and fitted them (old ones were way off spec). Also changed the caps on the display and control board - also way off. I also noticed some pretty bad soldering, which I reflowed. I also made sure all the rubber tips were in good condition. Connecting back up only gave a little improvement and most of the controls stayed dead.

Took it apart again and had a good look at the pins. I'd trawled the Vintage and Workbench forums for inspiration but there was nothing else suggested, so I decided to try another way. I used a fine needle file and drew it across the tips of the pins to get clean metal showing (obviously a gentle touch) on them all. Reassembled the machine and plugged in. Bingo! Everything worked beautifully. Seems that oxidation had got to the pins and compromised electrical conductivity to the rubber pads.

Worked for me, so I decided to share in case anyone else had similar problems and was ripping out hair. Not recommended to attack the pins with anything heavier than a fine file, and as little as possible to preserve contact with the rubber pads.  On to the CD5500..and the BM6000..  The fun never stops.