It probably has a broken hardware component.
Contact Sun's techsupport and get repairs.
If there is coverage by a Service Contract, then it'll be taken care of.
If there isn't such coverage, then expect to pay for service.
By the way, your forum posting is slightly off-topic and outside the scope of this forum..
The L100 is a tape library.
http://sunsolve.sun.com/handbook_pub/Systems/L100/L100.html
It's a peripheral.
It's a storage peripheral.
This is a forum for servers, not for peripherals.
(There are at least two other forums where it may have been more suited.)