This is a classic example of the kind of equine fertilizer that passes for fact among many Earhart "researchers." There is abundant documentary and photographic proof that there was no airframe switch. Earhart's machine was Lockheed Model 10E Special constructor's number 1055, registration number NR16020. The Model 12 "Electra Junior" is a completely different Lockheed product and has nothing in common with Earhart's aircraft. NR16020 was damaged in the Luke Field accident and was repaired at the Lockheed plant in Burbank. The engines, before and after the repairs, were 550hp Pratt & Whitney R1340 S3H1 Wasps (there is no such thing as a "Wasp Senior") with constant speed Hamilton Standard props. The engines were not changed but the props and hubs were, of course, replaced. There was also an approved modification that beefed up the landing gear attach points.
Paul Mantz was not removed as Earhart's technical advisor following the accident in Hawaii but he was not told that Earhart's "test flight" from California to Miami in late May was, in fact, the start of the second world flight attempt. Kelly Johnson was never employed by Earhart as a technical advisor. As a Lockheed engineer who helped design the Model 10, he worked with Mantz and Earhart prior to the first world flight attempt to develop fuel management protocols for AE to use on the flight.
Randal Brink's "Lost Star" (Norton, 1994) is perhaps the worst of the conspiracy books - quite an accomplishment.