HP Officejet Pro 7740 (Ink) Problem with the Supply System

[GJT3]

I had a problem with my HP 7740 Printer. The message came up on the screen telling me of a supply problem and pointing to the YELLOW HP cartridge. I replace the cartridge three times with new HP 952XL cartridges with NO success. I went on line and read about reseting the machine and tried that with NO success.

 I called HP to get support and hopefully get a solution to the problem. No answer from the support staff-"try back later."

• I finally decided to figure the problem out for myself and located the solution. 
• I removed all the cartridges and then removed the print head.
• I took a paperclip and straightened it out long enough to insert the end of it into the long tube of the yellow receptacle on the print head module. This tube is the male end that inserts into HP print cartridge. Thinking that some dried up ink was plugging up the receptacle I took the paperclip and inserted it into the receptacle as fas as possible [1/8 to 1/4"] and rotated the paperclip.
• I then reassembled everything back to normal. I turned on the machine. Everything worked as normal!!

The idea of supply problem makes sense, the machine is not receiving the supply of YELLOW ink. Dried up Ink must be lodged in the pathway preventing the flow of ink to the printhead.