For the last few months, my Kubota tractor has a steering problem that is getting worse. As it veers to the right or left, I have to turn the steering wheel a full turn in the opposite direction before it even begins to correct. I've checked the hydraulic fluid on the main dipstick and it is okay. Is there a separate place to check the steering fluid level? The power steering is also jerky for a while until it warms up for about 15 minutes. Also, how can I bleed the system to make sure there is no air in the lines?