The Epson print head has a thick rubber gasket between the part that pierces the ink cartridges and the main printhead, and this gasket warps with age and no longer seals. This may result in altered colours, muddy colours, sometimes even contamination of one cartridge with ink from another and is very occasionally responsible for spotty printing, as a result of air bubbles getting into the jets.
Happily, there is a simple fix for this – once you have removed the printhead from the printer. There are a couple of guides for an Artisan 1430 on u-tube you can search for: it’s worth looking at both of them before you start. A warning, though: take extreme care replacing the cables: misalignment can short out and kill your printer.