Deploy the flaps at a recoverable altitude and see what you need to hold to keep the nose level.

I have one plane with flaperons (modifed SPAD Debonair). The other day, I was flying for aerial video, and the plane kept pitching up. Turns out, the flap switch had gotten nudged so the flaps were fully up (more like spoilers). When the flaps are down, the plane will practically stand still, but it pitches the nose down.

Brad