Please confirm your printer model before purchasing to ensure it is suitable. In print entered please turn off the power of the printer, or it will cause the mainboard chip burned. After loading the print head, please don't install ribbon overhead 10 pieces of A4 document, so that make the new needle have a running-in process, and then put the ribbon. If the print head was broken and especially leaked ink, the mainboard has burned possibly,so please troubleshoot the problem of the mainboard before replacing our print head. In addition, the F1,F2 fuze wire of mainboard can only be replaced by the original fuze that has same current value and same model.If replacing fuze that is biger current value and different model, Both printhead and mainboard are possible to be broken. Print head requires lots of attention, It is easy to cause man-made damage if a non-professionals replace printhead blindly.Please do not make commissioning on the machine, and please treat it with caution. If you are not familiar with the machine, it is recommended that you had better send the print head to a repair stationor find professionals to replace the nozzle.