I am new to tractors/hydraulics with my recent purchase of a gas IH 656 with hydrostatic drive, and front loader. But, I am somewhat of a backyard mechanic. I am having big troubles with my IH 656 hydraulics/hydrostatic drive which just stopped working. All hydraulics, including the steering and the PTO. When I purchased the tractor a few months back, it ran and all the hydraulics worked (with some bubbles and a light milky color in the hydro fluid), but it was blowing radiator fluid into the oil. I diagnosed this as a blown head basket, and, over a number of months, finally got it replaced. As I just got it running again, and was adjusting it, and trying to run it a few minutes to check the true level of the hydraulic fluid, it started making a whining noise and it didn't sound good. That noise continued for a minute or two so I could try to check the fluid level. It appeared to be fine, was a golden color, with no bubbles and wasn't milky. I noticed that the fluid level didn't change from when it was off to after it was run for more than three minutes at higher rpm. Then, I tried to use the hydraulics, and nothing worked. Again, before I pulled the head, they worked - the loader, drove forward and backward, steering and the PTO worked. Now, none of them works. I called the Case IH dealer and he said that before I do anything, I should change the hydraulic filters. He asked me what the fluid looked like and I told him. Now, not having replaced any of the fluid after changing the hydraulic filters, the fluid is golden in color, clear, with no bubbles. But, nothing works. I suspect that the hydraulic pump isn't working because the hydraulic fluid level is the same when not running than after it is running for a few minutes at 1800 rpm (a little over the top full mark). The IH dealer thinks it may be a bad plate (like a fly wheel?) which comes off the motor which drives everything - broken/shattered or something because nothing is working - hydrostatic drive, front bucket, steering, or PTO. Is there anyway I can check for this, or check the hydraulic pumps, or whatever else may be wrong? Any help would be appreciated - this is my first tractor, and everything hydraulic is especially new to me. Thanks!