1010 RUS. Was running bush hog for about five hours today and hydraulic fluid started running out of the filler cap. Driving it home the hydraulic pump was making a high pitched whine. Not leaking when I got home but when serviced to full again, after 5-10 seconds fluid starting running out of the filler cap. Took cap off and fluid did seem to have air in it. When I shut off the tractor, the fluid continued to flow out of cap for a few seconds. I am guessing internal leak or plugged screen. When a load is raised on the 3 point, it bleeds down slightly and then bounces back up about every 15 seconds. This has been happening for a while but the fluid leaking out just started today. Any ideas?