640 print head be prefilled by vacuum technology, max storage achieves 30ml. Internal imported sponge has ultra strong capability of water absorbing and releasing, avoiding print head be spoiled for ink exhausted during normal printing. Prefilled ink will not run over with special design against ink leak during long sea and air transportation.LECAI 640 PRINTHEADSERRORSREASONSSOLUTIONSCut-off1.airleak of the seal between ink bottles and print head, 25ml inks become fewer and fewer till drying 2.unstable pressure of the different ink height state between the ink bottles and the print heads1.check the ink tubes and keep good seals. 2.fill ink as LECAI User Guide.InterferenceSometimes all of four heads have problems with jetting, it is OK we get off one, we call this interferance. The reason is someone head was short. The short head would interfere other three heads, even make them not work.Expel the disturbed print head with Lecai Printhead TesterFake BurntOften using bad print heads, it will cause the contacts of Flex Quad become cupped till scrapped.Expel the disturbed print head with Lecai Print head TesterLower ResolutionThe unreasonable distance between the print heads and mediaAdjust the height correctly and check the calibration parameter