If you have to undertake fixes on your Rieju SMX 50 Pro then it is usually a good idea to own a Workshop Manual to keep just for personal reference in case that you want to know the best ways to take out a specific component for instance the Gearbox and fit it again in the right way.
Rieju SMX 50 Pro Workshop Manuals are able to offer certain diagnostic info with regards to your vehicle therefore if something is wrong it can help you understand what the issue is and the best way to resolve it. After that you can decide if this can be done on your own or that the job is just too big you can actually make a reservation for your SMX 50 Pro into a decent car garage.
Rieju SMX 50 Pro manual