If you have to do fixes for your Rieju 125 NKD then it will always be a good plan to own a Workshop Manual to use as a guide in the event that you need to know the right way to strip off a certain part like the Brake Discs and fit it again perfectly.
Rieju 125 NKD Workshop Manuals can offer you particular diagnostic info with regards to your vehicle so if something is not working it can help you ascertain what the issue is and the way to correct it. You can then assess if this can be achieved by yourself or in case the job is just too big you can make a reservation for your 125 NKD in to a suitable friendly mechanic.
Rieju 125 NKD manual