Solid yellow and green lights on hp 1220c

SOURCE: HP Deskjet 1220C cartridge recognition problem

try to clean the ink carriage

SOURCE: HP Laserjet 1300 printer Yellow light flashing

Normal 0 Driver could be corrupt.
Disconnect the printer or at least be sure it is turned off. I'd do both and reinstall the CD software program that came with the printer. When the software program asks you to connect the printer to the USB port, do so and it should again work properly.
Hope this helps. Bud

SOURCE: 1220c Ink blockage

Have you guys checked that the yellow is actually coming out of the cartridge?

Its easy to check. Take cartridge out of printer. Clean bottom of cartridge where ink comes out (usually on flat metal with microscopic holes below the metal contacts) with kleenex. Place piece of clean kleenex under bottom of cartridge where ink comes out. Gently press on cartridge - see what colours you have on kleenex. If you don't have yellow, but do have cyan and or magenta, then cartridge is blocked (regardless of whether its new or not). Cleaning and priming will not work if jets are blocked with set ink.

This can be tackled!

Take one kettle, boil water!
Steam the metal jets in the kettle spout for a few minutes
Place cartridge back on clean kleenex - if still no yellow try again. If yellow, then move to clean piece of Kleenex and repeat until all three colours regularly appear on kleenex after around 30 secs.
Place cartridge back in printer
Repeat clean and prime cycle until good test pattern produced.
Fixed!.

SOURCE: HP Deskjet 1220c Orange and Green light on

TRY LUBRICATING THE SILVER SLIDE BAR WITH SOME SEWING MACHINE OIL,DONT GET OIL ON ANY OTHER PARTS