I have a Kubota L3240 HST about 8 years old with 900 hours. I was mowing grass with no problem. Turned the machine off for half hour. When I came back and started it up the tractor had very little power. Barley took off when giving it gas. When I throttled up it seemed to have loads of power and took off fine, but throttling down it has no power. The hydraulics on the mowing deck and bucket all work fine. Never had this problem before and can't figure it out. Thought maybe a button had been pressed accidentally on a selector, but all seems good there. This has me stumped.