If there are more than one failures then check how they map to the MACB HDMI connections.
 Are they all connected to the just one MACB ? => Check the HDMI cable at the MACB Layer Port.
 Are they all connected to several MACBs which have a common "Parent" ? => Check the HDMI cable at the "Parent"
MACB Layer Port.

If there is just one failure then open the Local Controls browser window for the failing FEE64.
If the "Status Register" @1 is not 0x7 then the Waveform ADCs will not operate correctly and ASIC readout will
be compromised.
To remedy try 
A)    Enter 0x2B to "LMK03200 control register" @5 
          then Reload the Page 
          then Enter 0xB
          then Reload the Page and check the status, if 0x7 all ok. 

B)     Enter 0xA to "LMK03200 control register" @5 
          then Reload the Page
          then Enter 0xB
          then Reload the Page
          then enter 0x2B to "LMK03200 control register" @5 
          then Reload the Page 
          then Enter 0xB
          then Reload the Page and check the status, if 0x7 all ok.