I wonder why O'Brien didn't just replicate the materials and build a new beta-matrix compositor.
Some elements would seem to require either human construction or require a grade of material that cannot be cheaply or effectively replicated. Perhaps monetary-grade latinum cannot be replicated. Perhaps a particular grade of latinum is necessary for creating gold-pressed latinum. Perhaps there is an aesthetic quality to some latinum that cannot be achieved in a replicator. It might be similar to the difference between industrial-grade diamonds and what someone would get in a ring.