Pertinaxed

I've been playing FC3 with profit and enjoyment for months, but after installing 1.2.8, I can no longer use throttle step in the F-15C. I was just using the default bindings, page up and page and page down. Gradual throttle adjustments (numpad +/-) still work, just not the stepping. Even though the game told me that it was using the default bindings, I tried rebinding the keys, both manually and using the "default" button. No dice.