Roland printers:

Clogging within the pump area occurs always direct inside the pump itself. Why?

The tubing attached to the pump and direct the ink in to the waste ink pipe is made out of one piece so there are no obstructions in this tubing and therefore most likely no clogging.

The pump however need to push the ink first an inch upwards through the pipe with the affect that when the pump stops the ink remains within this inch of tubing will flow back into the pump where it then will clog after time.

Clogging will only occur when the printer is out of duty for some period of time and faster because there is direct air contact in this area.