People just beat on those cameras. Many were sold to students, or were part of an academic program, same issue. I used several on the job from about 1985-90 and my predecessors there had beat on those. Yet they always worked- we had a box of spare parts sourced from Calumet just in case. Looks like you have good advice from the previous posts. The 402 was the long-rail version, 22", correct? I don't know where you'd find parts now; Calumet has been gone for a decade. with the prices for used Sinars so low now, maybe it's time to switch systems.