How to physically identify the faulty disk on a Sun Fire X4200 hardware raid

Hi , would like to ask our experts in the community how to physically identify and replace a faulty disk on a Sun Fire X4200 configured as a hardware raid. i can see which disk is failing from raidctl but can't identify which disk to physically replace as there's no amber led on the disks. thanks in advance for any help.

 # /usr/sbin/raidctl -l c0t0d0
Volume                  Size    Stripe  Status   Cache  RAID
        Sub                     Size                    Level
                Disk
----------------------------------------------------------------
c0t0d0                  67.9G   N/A     DEGRADED OFF    RAID1
                0.1.0   67.9G           GOOD
                0.5.0   67.9G           FAILED