Scott, I'm amazed it's happened to you at all! I had never seen it, or even heard about it. I thought it might have been a one-off problem.

When I was at Otis, I was compounding the generator on an MRS unit. It was 1990...Gas was a nickle, and dinosaurs ruled the earth..where was I? Oh, yes, for every turn we added in the series field, we should have gotten a linear effect in the base speed, but the speed jumped wildly when adding what should have been just another turn. Sure enough, the series field taps were mis-marked, and there was a couple of markers in the wrong place. I thought it was a neat problem, because the empirical evidence demanded a rational answer, even if that answer contradicted assumed constants. God, I love that sh*t! fun to think about, fun to solve. Sometimes daunting! Gets your brain working! Still hate Sudoku, though.... :^)