how do I check the transmission on my RanchKing 18/46 hydrostatic mower?

the engine and blades work fine. when I try to mow it runs fine for 5 min or so but then starts slowing down. after 3 or 4 more m in it stops moving--with engine and blade still running fine. After a 10 min shutdown it will run ok for another 5 min or so. no effect on engine or blade rpms. seems to be strictly transmission related. Does it use fluid? could it be low? how do I check and fill it? I inherited it and do not have any manuals

the other DWS, April 2010

Hyro units usually run on multi grade oil, if the oil has not leaked out on the garage floor it will most likly still have enough, heat is the biggest killer, check the brake is not binding, if it has a resivoir, check the oil level here, as the machine heats up the oil gets a little thinier, if there is any scaring on the internal centre section it will get slower and slower until it stops, i think you have a problem like this, it would need to come apart and see how much damage has been done, this can be a very expensive rebuild with the cost of new parts.

Husqvarna man, April 2010