Planning for manufacturing workpiecesis a complex task that requires the interaction of a domain-specific reasoner and a generic planning mechanism.In this paper wepresent an architecture for organizing the case base that is basedon the informationprovidedby a generic problemsolver. Aretrieval procedureis then presented that uses the information provided by the domain-specificreasoner in order to improvethe accuracy of the cases retrieved. However,it is not realistic to supposethat the case retrieved will entirely fit into the newproblem. Wepresent a replay procedure to obtaina partial solution that replaysnot onlythe valid decisionstakenfor solvingthe case, but also justifications of rejected decisions madeduring the problem solving process. Asa result, those completionalternatives of the partial solution are discarded that are already knownto be invalid from the case.