If you wish to do maintenance tasks on your own Suzuki Bandit 1200S then it is always recommended to possess a Workshop Manual to use as reference in case that you need to know the best way to remove a specific part like the Clutch and install it again appropriately.
Suzuki Bandit 1200S Workshop Manuals are able to offer detailed diagnostic guides for the automobile so if something is wrong it will help you identify what the issue is and some ways to fix it. You will be able to evaluate if this can be achieved yourself or if the job is just too big you can actually book your Bandit 1200S in with a decent car garage.
Suzuki Bandit 1200S manual