Greetings,
I would first suggest that, if this device is in a system connected to the internet, you run the Online E Series Diagnostic. This utility will test the functionality of your board and perform a self-calibration. The link to this utility is available below:
http://ni.com/support/selftest/
Unless this calibration fixes the problem, I would create a phone support request at the following location to arrange the repair of your board:
http://sine.ni.com/apps/we/niae_asc.main
Best.
Spencer S.