I'd suspect a cold solder joint, it's about all there is left to consider. The fact that the player seems to find hda but can't even read its partition table would seem to imply one of the lines in the ide bus isn't working. Mark will certainly have a better idea than I would of the details here.

Try starting the player up while pushing down on the connector where the IDE cable plugs into the empeg main board. Also inspect the IDE header with a magnifying glass and see if you can see any cracks.

Matthew