In experience-based (or case-based) reasoning, new problems are solved by retrieving and adapting the solutions to similar problems encountered in the past. An important issue in experience-based reasoning is to identify different types of knowledge and reasoning useful for different classes of caseadaptation tasks. In this paper, we examine a class of non-routine case-adaptation tasks that involve patterned insertions of new elements in old solutions. W e describe a modelbased method for solving this task in the context of the design of physical devices. The method uses knowledge of generic teleological mechanisms (GTMs such as cascading. Old designs are adapted to meet new functional specifications by accessing and instantiating the appropriate G T M . The Kritik2 system evaluates the computational feasibility and sufficiency of this method for design adaptation.