Long 560DT power steering

[Tractorookie]

I just bought a long 560dt with front end loader. Doing the servicing and trying to figure out what’s going on with the power assister steering (non hydrostatic steering). It almost seems like the pump is bad as it steers really hard when you’re not moving. Also the fluid is pretty dark but doesn’t seem like it’s contaminated with water or anything. Does anyone have any tips on how to tell if the pump is bad or just needs to be flushed out? Or if anyone has any helpful tips on the tractor as a whole would be much appreciated. Thanks.