MZ/MuZ Riders

Hello All,
I am new at this forum, and I am Omer from Turkey. I bought a 2002 Mz Sx 125 almost 3 weeks ago, and it is pretty rare in my country. But I like my bike pretty much. However, it has little problems since it is 2002 model.
There is a problem at front brake fluid reservoir. It is leaking brake fluid, but I couldn't really understand if it is from master cylinder or somewhere else. Previous owner told me it is from master cylinder and because it is original he didn't want to change it with something new.
Therefore, my question is if it is from master cylinder, can I find non-oem master cylinder for this bike since it is pretty hard to find original one.
Or should I change whole reservoir with something non-oem? If I do it, can I just buy a random one or any dimensions or recommendations?
I am sorry that I am pretty new at those things, so maybe I am asking something looks stupid.
Thanks in advance
Omer

some of the parts i have seen
seem to be from Thailand
look at bikes from Kawasaki and kymco scooter
lot of stuff on my mz rt125 match up
your 125 may have been one of the bikes assembled in Malaysia

the diameter of the piston needs to be the same but some other master cylynder should work

Alright, I will check Kymco and Kawasaki dealers. Thanks a lot!