Greens ranger MK3A mower

Hello from BE

i've just get an towed mower from GRENNS 

on the label is writen MK3A

it is very hard to pull him and i wanted to pull with anothe rone with a 2wheel traktor (Agria 3400)

So my idea was to have look in hte transmission, if it is clean and well "oiled"

But before opening i want to know what is inside.

Does anyone of you know where i can find plan or drawings from this transmission ??

many thanks from Belgium

Manfred