I've been having trouble with my pedalling lately with large works with wide pedal parts. The problem is getting my seat turned so I can reach the low pedals with my right foot and high pedals with my left.

I've tried moving the bench back so I've got less "seat" on the bench, but that seemed unstable. I've tried lowering and raising the bench and raising seemed to be the better of the two.

Maybe it just needs a good polishing?

That's a very familiar problem. I've had similar problems when I was first learning how to navigate the pedalboard.

For me, it was a matter of figuring out the best height to position the bench. I regularly play a couple of organs - one of them has an adjustable bench, which I just simply turn the crank until it comes down to a height I'm comfortable with; the other has some blocks at the bottom which I remove, and then the bench, while still a little high, is not too high that I can't reach the pedals with my heel.

I've had the uncomfortable experience of literally sliding into the pedalboard when the bench was situated too high. Too embarrassing, never again!