If you need to do fixes to your Jawa 50 Robby then it is usually a good plan to have a Workshop Manual to use as a guide should you need to know the best way to take out a particular part much like the Clutch and install it again appropriately.
Jawa 50 Robby Workshop Manuals can offer you specific diagnostic guides for the car therefore if something is wrong it can help you understand what the situation is and the way to resolve it. You can then evaluate if this can be done yourself or if the job is too big you can book your 50 Robby in with a suitable repair garage.
Jawa 50 Robby manual