If you need to do auto repairs for your MZ SM Gangsta then it is always recommended to have a Workshop Manual to keep just for personal reference if you want to know tips on how to remove a particular part including Gearbox and fit it again in the correct manner.
MZ SM Gangsta Workshop Manuals will give you distinct diagnostic information with regards to your automobile so if something is wrong it can help you identify what the situation is and tips on how to resolve it. You will be able to decide if this can be done on your own or in the event the job is too big you can actually make a booking for your SM Gangsta in to a nearby friendly mechanic.
MZ SM Gangsta manual