301 Fluorescent lamp troubleshooting
If just one of your lamps is out verify it by switching the two lamps. If the problem follows the lamp you need to replace it. The X-RITE's part number is SD105-06,
The commercial number is F6T5/D.
If the problem stays on the same side it could be a failed holder, ballast or the switch.
Failure of both lamps at the same time is usually the switch. Service would be recommended because of some changes in this area. The switch has been changed and can't be retrofitted in the field.