Have have a 16 hp Walker Mower that is probably 10 plus years old. I got the engine running strong again but I am having an issue with the Hydros I think. When I am moving forward and want to turn the mower starts bucking. If i slow down and then turn it is not so bad. Any thoughts about how to trouble shoot this would be greatly appreciated. I am pretty good with engines but not too familiar with Hydros. Both oil reserves are at the right level.