Depends on whats worth it and what is not. Perfect cranks were soft aluminum. They sawed through, definitely. Fox cranks are tempered better. IMHO. How long will this trainer be flying and will it be honking. Cut a couple of inspections hatches in the bottom, CA them back in. If the plane is o.k at the end of the season, not likely if it's a trainer, cut the hatches out again, take a look and replace. One of the most frustrating things about other people's builds and ARFs is the darn controls. Usually the worry is not worth the time.
Howard is funny.