For producing real thick paperbacks for our booklets we got an used Epson Stylus Photo R2400, which can print to material up to 1,3 mm thickness. The printer seems to be ok, 4 of the colours (the left one of the printhead) print well. The right 4 colours do not print at all. This means no stripes, no problems, no colour at all is printed to the paper. I cleaned the printhead, and the head is completely free. I can also put IPA through it, and see that all the nozzels seem to work. So this is for 100% no "printhead cleaning issue" anymore. Also the ink of the non-printing colours is dissapearing like at the 4 working ones, when I clean the head by software.

So I checked all the cables to the printhead and they are ok as well. The service manual is of no help regarding this problem. I suspect something of the pump mechanism, but donīt really know. Can anybody lead me into the right direction? What should I try next?