How do you adjust hydros speeds

[Horsepower Lawns]

on an older Bunton. How do you adjust the speed so it will go straight.

I have them adjusted so it will not move when out of "gear".

Thanks.

[ChadsLawn]

Need to give alittle more information.. What type of Buton are you talking about?

[Horsepower Lawns]

Sorry I posted just before I left for work.
BUNTON MOWER Walk behind
MODEL # BHT14KW
36" DECK
KAWASAKI FC420V MOTOR