So what's the secret to removing and installing the orange hydrostatic transmission control knobs on a 300/314/317/318? I thought that years ago I had unscrewed one on a buddy's tractor. I recently tried removing a faded one with the idea that I will replace it with one that is not faded. I pretty much destroyed it getting it off. it did not unscrew. I had to use brute force and ignorance to get it off! Are these meant to be replaceable?