That IDE header has been resoldered by someone after it left the factory,
and looks good to me (from the photo, anyway). Check the cable?

The residue around the pins is the flux from the solder,
and is probably of the "no clean" variety (mostly harmless).

The little corrosion around the mounting screw doesn't look serious.
If you want to clean things up, then ground it and you (for static discharge),
and use a swabby thing moistened with alcohol.

Cheers