John Deere 35c

Hello everyone. I am new to this forum and in much need of some help. I have recently bought an early 2002-2005 John Deere 35c mini excavator that has some issues; one is that it lacks power on swing motor, its really slow at making a 360 degrees turn either way left or right. Another issue is that left track is really slower than the right one; at the point that it stops if right track its not moving forward or backwards. Finally, hydraulic oil overheats (have not measure temp yet, but read that hydraulic oil can reach up to 180 fahrenheit), the hydraulic controls on joystick turn pretty hot at touch, I have done basic maintenance like engine oil change, cleaned and drained radiator, fixed most of hydraulics leaks and greased most of grease points. I will appreciate all the help, advice, tips or tricks anyone can provide me with.

Thanks in advance,
Att. Henry Sanabria