i HAVE A HP OFFICEJET PRO X476dw MFP printer. I came back from holiday and tried to print and it said one or more cartridges appear to be damaged. So I watched the video and replaced the yellow. It continues to say it is damaged. I have replaced it with 2 other cartridges. The video also shows that I need to clean the end of the cartridge which I did. How do I clean the inside electrical post contacts?