Ink Color Not Printing-HELP!

I am absolutley brand new to this site, forum print busness & am so impressed by all of the help members offer one another, so I am hoping someone can help me please. I have a Roland XC-540. Only one other time did the color not print out correctly (I think it was the magenta), but it was under warranty & so the tech fixed it. I didn't watch too closely (my mistake) as I was working on orders, but he did have to replace what looked to be a thin piece of tubing. I am not sure if he replaced only the plastic tubing or anything else. Well, it is now 6 months past that time & my warranty is up & my printer is not printing colors out correctly. I am trying to print an order that has red, white & blue (the flag colors). The blue prints out much lighter than the deep blue it should be. The red prints out in yellow!! I also printed another order that is black & white in color. The black prints out in an olive green color. I have learned to tinker a bit with this printer as I am new to this, but my husband is very mechanically inclined, but has not worked on this printer yet. Can anyone provide me with some tips or advice on what to have my husband check out, take apart to look at, etc??? I am trying to avoid a service call w/o having the warranty coverage as well as I live a 4 hour round trip to the nearest tech. Many thanks in advance!!! Kelly