System cannot boot, looks like Hard disk crash

MAC OS Lion, system fail to boot.

Boot Target Disk Mode, I can check all contents in the hard disk.

Boot Single User mode, saying "I/O error", but fsck is OK

So I assume hard disk crash. Swap in a new 500G HD. Use USB drive for Lion Recovery Disk. It cannot see the new HD. Swap back the old disk, it can see it but fail in partitioning.

Hard press the "SATA" connector on the Logic board, the Lion Recovery process can see the new HD, restore from time machine. Everything fine but the system is not stable, it fails frequently. Hard press the "SATA" connector will let it works for a while then fail again.

Put the old HD in USB external enclosure, the HD works OK. It proves nothing wrong with the HD.

Should I change the "SATA" cable?

Any chance of SATA port failure on Logic board?