Kubota M8200 steering problems

[Leghumper]

I've got a 4WD Kubota M8200 and the steering is really choppy. I've checked to make sure that there's no obstructions or anything obviously wrong with the steering or with the hoses and without breaking into it, I'm not sure what else to check. Anyone have any ideas?

Thank you

 

[art]

When was the filter and oil last changed?

 

[Leghumper]

When was the filter and oil last changed?

2010....not quite 1000 hours ago...it's been an issue for about 500 hours. When the RPM is high, the steering seems to work fine....just when at low RPM, it's not.