Looking for any ideas on why the hydraulics for loader and backhoe just quit. Tractor drives fine. Pump is spinning (at least when viewed externally). Fluid level perfect. No leaks anywhere. New filter. Backhoe couplers unobstructed and definitely attached. I heard a squeal coming from area of pump when problem originally started that has since gone away. Removed inlet hyd. hose from loader control, started tractor, nothing. Have read numerous accounts on internet and TF and have come up with nothing. Keep hearing about the relief valve. Cannot find one in any of my parts illustrations. Would love to hear from the experts. Thanks