This is how I found which colours went where on my Deskjet 3822 hope it helps.
If you're unsure which colour goes into which chamber, wipe the copper printhead with kitchen towel and insert the hypodermic needle into one chamber. Gently blow into the needle while holding some kitchen towel over the printhead. Wipe clean and mark that chamber fill hole with the colour that appeared. Do the same for the other chambers.