There are indeed different cables for the 400K and 800K drives where the wrong cable can cause constant ejecting of the disk. However I think the cable is not the issue here as the drive started failing while it worked before.

400K drives NEED pin 20 and 9 (spindle speed and -12V respectively), whereas some models of 800K drives can get confused by these two being connected.

The early drives use the cable with the yellow wire, the later models use the cable with red wire.

I think with the red cable not all pins are connected.