Checking the Eaton's hydro fluid levels

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My Swisher ZT2560 has only a parts location manual with basic adjustments you can make and covers no "how to" maintenance procedures at all.
I am a mechanic of sorts and can maintain this mower using the oil change, lubricating, and tune-up procedures I've learned from hands on and help in these forums.
I need to know how to check the fluid levels in the reservoirs on the top of the left and right drive Eaton hydros. The mower drives and steers very well.
Currently there is no oil in the reservoir with the engine NOT running.

What type of oil is used and how do you check the levels and bleed the system if needed...Tom