if you swapped a non printing yellow damper/line to a printing magenta damper/line. and the magenta line would not print at the yellow position, but the yellow started printing at the magenta position. and your cap shares yellow/magenta (which i believe it does). and you switched heads to the same result, then you have to assume that you have a data issue at the yellow print head position. it could be a bad data ribbon connection, or frayed data ribbon, bad fuse on a slider board, or bad fuse on the main board.
looks like you need to do a data swap. since your printer has two heads, you will send the black/cyan data to the yellow/magenta head and vice versa. attached is a data swap diagram for a jv3 160sp. don't do this if you have any misunderstanding or doubts about getting it right. if done properly the printer will assume that all is well and send the data to the wrong head. because it doesn't have knowledge that the head isn't where it used to be. if hooked up wrong, you will loop a charge the wrong direction through the head. so... ask around if in doubt.
after the data swap, if yellow suddenly prints yellow (you would send it some cyan data in order to do this), you will know that the head is fine, but the cable or board or slider board isn't. but first isolate if the yellow wakes up with cyan data.