Danny42C had, earlier in this thread, suggested that, in light of his experience with PT-17s, the prop could have inadvertently, prematurely been knocked into coarse pitch.
Here's a cockpit picture from Ewald's website:
I have only flown a fixed-pitch Stearman, so I wasn't sure where the prop control would be. I notice that the mixture and prop knobs are very similar, so I could see how you might push the mixture control to Full Rich if you weren't looking. Perhaps Danny could comment?
Also, what's the red lever below and aft of the throttle quadrant? I've forgotten.