The printer has in the base a large abosrbant pad
that takes up surplus ink.
It is now full.
Under the the cartridge track you will see a hole with a black blob in it soft to touch - touch it and get an inky finger.
They say there are replacements available - but I have yet to find them and it does mean taking the printer to bits any way.
My P/Stylus750 went the same way After much heartache I went and bought a R300
Perhaps this is the way to go