Hello friends, I've had this printer for quite a few years now, I only changed the toner cartridges over the years, now, I'm having this issue with my printings, as you can see on the images, color is printed quite acceptable, but black is another issue, my printer manager says black toner is 50+%, so I don't know what could be, I dont want to spend a lot of money on parts like a transfer belt, image unit or a black toner and get the same results 
Any help and/or advice would be very appreciated. Thanks in advance.
Any help and/or advice would be very appreciated. Thanks in advance.