Could someone tell me what is the correct print head for a cj 500 converted to eco solvent. I just bought this machine and am going to attempt to clean the 2 heads. If that does not work I want to make sure i purchase the right ones. Are they they Dx4 or Dx2. Also in some place's i've read that you need to buy a left one and right one. Does that sound right, are they like buying a pair of shoes? Thanks for the help in advance.