T2000 Spurious CPU Fan Fault

We have a Sun Netra T2000 (Sun-Fire-T200 32 CPU) with 3 CPU fans, one
of which is reporting a fault:

ALOM> showfaults
  ID FRU               Fault
   0 FT0/FM2           SYS_FAN at FT0/FM2 has FAILED.
ALOM>

The machine is out of contract.  I tried swapping the faulty CPU fan
no. 2 for no. 1 and it still reports that fan no. 2 is faulty.

I tried clearing the fault but it didn't seem to understand:

ALOM> showfaults
  ID FRU               Fault
   0 FT0/FM2           SYS_FAN at FT0/FM2 has FAILED.
ALOM> clearfault 0
Invalid UUID format.
Error: Invalid command option
Usage: clearfault <UUID>
ALOM>
ALOM> enablecomponent CH/FT0/FM2
Could not find asr-key CH/FT0/FM2
ALOM>

The last message about the fan in the showfru command states:
/Status_EventsR[9]/Message:               SYS_FAN at FT2 is OK.

I tried resetting the SC, power-cycling the whole machine and the
clearasrdb command to no avail.

prtdiag reports:

============================ FRU Status ============================
Location                           Name      Status
------------------------------------------------------
0707NNN065:CH/FT0/FM2              FAN       disabled

Does anyone have any suggestions?

Regards,

Nick Pettefar