I'm liking motownbrowne's ..... 'adjusting a stop nut' and the dealer's suggestion of obstruction preventing full pedal travel. It's strong enough in reverse so speed according to the dealer mechanic should only be pedal travel .... swash plate opening yada yada / HST. As far as adjustments on valves goes I went through the shop manual looking for an adjustment, also asked the dealer mechanic, I think you're right no quick adjustment available.