Knowledge refinement tools assist in the debugging and maintenance of knowledge based systems (KBSs) by attempting to identify and correct faults in the knowledge that account for incorrect problem-solving. Most refinement systems target a single shell and are able to refine only KBSs implemented in this shell. Our KRUSTWorks toolkit is unusual in that it provides refinement facilities that can be applied to a number of different shells, and is designed to be extensible to new shells. This paper outlines the components of the KRUSTWorks toolkit and how it is applied to faulty KBSs. It describes its application to two real aerospace KBSs implemented in CLIPS and POWERMODEL to demonstrate its flexibility of application.