None
If the IF Frequency Response Test fails, the most likely caused by the A2 Analog IF. Less likely is the A3 Digital IF. At wide spans, the RF flatness could be a contributor. Perform a frequency response verification to see if an adjustment is necessary.
If Option B1X fails IF Frequency Response, then upgrade to firmware above A.08.00. This will install an improved IF flatness alignment which should fix the failure.