Digital BW, The Print

Hello,
The color add ink light on my Epson 980 will not stay off after I do 
the change cart routine.  It goes out when I return the head to home, 
then goes on again after a new page starts to print. Is there a 
sensor relating to the waste ink sump that needs attention? I use 
quad blacks and do a lot of refilling and head cleaning.  I pulled 
the tubes that run from the head pads to the bottom of the chassis 
and let them drain into a jar. Also I made sure they were clear. 
Seeing how much fluid is used in a cleaning cycle was a real eye-
opener!


Any help will be appreciated.