Should be easy to determine if its the pump, simply lift the top and
see if you can see ink flowing through the plastic waste pipe thats
connected to the underside of the docking bay, if you switch on or go
through a cleaning cycle the ink should easily be seen flowing in the
pipe.

If it comes away there will be a good chance of ink spillage on the
bottom of the printer, another quick way to see if it came detached
(which is a common problem with the C series), get a pencil and see
if you pipe is easily moved, if its loose it will easily flop about
at the free end.

All the pump is is a gear from the paper feed rollor and a rotating
disc with a little bump on it like an hammer, since the tube is
coiled in a circular mannor, the bump squashes the tube as it rotates
in a circular motion causing the ink to be sucked.

Art refered to it as a mini milking machine some while back which is a
very good description.

The pump don't work, the ink is'nt sucked from the heads and it dries
up causing clogs, which is pushed back into the nozzles by the wiper
blade.

Davy