Steiner 440 loud hydraulics

[Oaklie]

I am new to the forum and looking for insight on my Steiner 440. I just purchased my first Steiner tractor and had a question about a noisy hydraulic pump. When the tractor is under a load the hydraulic pump sounds like it is screaming. As soon as I am mowing flat or going down hill it sounds normal. I own a construction company and have several hydrostatic pieces of equipment but never heard anything like this. Could someone give me any tips to quiet down the hydraulics? My tractor has the 34 hp Kohler engine and I am mowing with a 72” Ventrac finish mower. The tractor seems to have plenty of power mowing thick grass at any speed just very noisy. Any information would be greatly appreciated. Thanks