I really suggest making sure that the cable has a secure connection at both the drive AND the board. Since you've opened up the case a few times, it's possible that something has some loose. You really need to push on the things to get them to hook up. Visually, there should be no gaps, even slight, between the connectors.

Some people think I might even have a "dry solder joint" which also gets "fixed" by pushing down on the cables.

Also, since moving the drive to the other cable spot helped for a bit, I suggest contacting support for a new one in case you ever add another drive.