SunFire v240 hardware question

  So I have a SunFire v240 I'm planning to swap in to replace an older USparc-II machine.  (E420r).  The v240 is reporting:

SC Alert: CPU_FAN @ MB.P1.F0.RS has FAILED.

  which I know means one of the [two] heatsink/fan units has a failed fan.  I'm using this list to reach people who may well understand the problem, and the solutions, and I have two questions.

  (1) Is this a problem?  I mean, if I'm not going to be pushing this machine hard, do I need to worry about it?  (It will be mostly a mail server, pretty lightly loaded, CPU-wise)
  (2) How _hard_ is it to replace said fan?  Anyone done it?

  I've replaced fans in lots of equipment, sometimes even CPU heat-sink fans.  But, that often requires removing the sink from the processor, which is something I'd rather not do if avoidable.  I have a few types of heatsink compound, all many years old, but likely adequate, I'd just rather not if it could be avoided.  :-)

  Thanks...  All thoughts welcomed.

                     - Chris