My trusty Advantage A1 pedals that served me well for 8 or 9 years have finally given up the ghost. I'd noticed that my pedals kept going only to about 90%, even after I kept calibrating them. The range of movement was getting smaller and smaller. I opened up the case, and found that the throttle pedal was actually cracked and bending at its pivot point inside the case, so I was just bending the pedal more and more instead of turning the pot, hence not getting to 100%.
So now I've gone to the Thrustmaster pedals that came with my wheel. Rock steady pedal input now, and a good range of motion. The brake pedal has got some kind of pseudo-brakecell mod, with a rubber pad and a stiffer spring at the end of the travel, which will take a little getting used to. But so far, so good.