I noticed that my tractor hydraulic system is starting to get hot lately. I recently replaced the fluid, filters and cleaned the strainer. I also replaced all rubber suction hoses. I put in a new 0.2 mm shim and 2 washers in the relief valve as when I took the relief valve plug out, the previous washers and shim were worn out. I did all that because it was time to do it plus hoped to improve performance. When the hydraulic fluid gets hot, the FEL becomes weak and the tractor whines some when I drive it around with FEL bucket full of dirt. The joystick housing on the FEL becomes hot to touch. I checked the fluid level and its within the range. BTW I used UDT. Is it the hydraulic pump that is failing? Could it be the hoses on the FEL? I checked the strainer and there’s no metal shavings in it. Most of the time I had the engine at around 1,800-2,000 RPM when digging up, moving, and dumping the dirt until the tractor started to whine and FEL became weak. I tried increasing the engine to 2,400 RPM (PTO speed), the whining stopped when moving but still would whine seldomly when lifting the loaded bucket. The FEL moved slow.