The 4600 will be somewhere between 10 and 14 years old, so I'm pretty sure we're not talking eHydro. I have the HST on a smaller JD, and had to buy an odd-sized metric impact socket for the job. It was of a size you don't typically find in a standard metric set, 14mm I think. Anyway, it was needed to break free the hex head that holds the reverse pedal in position. I'm guessing they used some kind of thread lock on it. Once it was free, repositioning was simple. I didn't reapply and thread lock, and it's still holding position after 3 years.
//greg//