sp-540v ink line contamination

Take the ink cartridges out and then pull with a syringe through the damper to suck the ink out. Just get the bulk of it out. You don't have to flush most of the time but you could if you want to make sure all the pathways are nice and clean. If it were me I would just get the magenta out of the yellow and then move on from there. There isn't enough magenta left over in the line to change the color of the yellow in any meaningful way. Just be aware that if the ink receded back far enough to get into the cartridge, you might just need a new yellow cart. Pretty rare though.