Hello. I came across this question hoping to see a answer. I'm guessing you didn't get one. I believe that I am also having the same issue. Except that the reverse is fine. Forward is the issue. Here's my e male if could reply, thanks.
Lemonlimehomer70@hotmail.com
And a fuller answer to your question.
I have a tilt trailer that I use to collect customers mowers
The hydros are tested when I load & unload the mower.
When loading the bypass is activated so I can see if the brake is dragging .
When unloading the bypass is turned off & I give the mower a push
If it is hard to push with the brake off and stops when I let go then the hydros are in perfect working order.
If it races away the instant I remove the brake the hydros are deceased
Some where in the middle I can make an assesment of the life remaining .
Once they keep going when given an initial push they are on their way out .
Hydros have a finite life and the thing that kills them really fast is driving with the engine running slow.
My older customers tend to do this in the belief that if they run the engine slow it will last longer