Changing Hydraulic Oil

[Stepside]

I'm hoping that some of you guys can give me some advice on how to change the oil on my Leimbach Excavator.

I took some pics of the hydraulic system and labeled each connection to make this a little easier:






1:
2:
3:
4:
5: Reservoir Breather
6: Reservoir Breather
7:
8:


To, it looks like fluid is pumped from 2 into the filter at 4, out of 8 and into 7 to the value body.... then out of 3 and back into the pump at 1. !!!

My questions are:
A. What line do I remove and put into my new fluid?
B. Do I need to service the filter?
C. I assume I also remove the reservoir and put new fluid in

Or, a better way, is how do you change the oil in a machine like this?