Do you have a diagram of the shift pattern to look at? There is a neutral position that runs sort of front to back on the tractor and it can be tricky to find sometimes. I am assuming that by high range, you are referring to the forward set of gears, these aren't neccessarily high range tho'. You will know when you find the gears in the forward shift pattern, the shift lever will nearly touch the dash.   Does this help any? I believe it is a 1955 tractor.
              Cal