Does anyone know why the low, medium, high range gear is hard to shift. And it wont go into high range? Before it did this, I noticed the roll-pin had come out a little. I knocked the roll-pin back in and worked fine for a while. Now it is hard to shift again and wont go into high range, the roll-pin is in place? Is it because the roll-pin is weak? do I need to replace it or is there something else wrong with it? any thoughts appreciated.