2000 Dodge Intrepid valve noise

My daughters 2000 Dodge Intrepid has what seems to me to be a rocker arm rattle. If after I get this valve cover off and discover a collapsed rocker arm slack adjuster or broken valve spring....can I replace only the broken parts such as the slack adjuster, rocker arm or valve spring or do I need to replace all of them for that valve head bank ????? also ..do I need to use the special valve spring compressor or is there another way...those fixed bar compressors are hard to find.....lastly are these slack adjusters prone to collapse ????