If you wish to accomplish repairs on your own Sym GTS 125 then it will always be a good plan to have access to a Workshop Manual to keep just for a guide just in case you need to know how you can strip off a certain component for example Brake Discs and install it again appropriately.
Sym GTS 125 Workshop Manuals will provide you with distinct diagnostic information for the car or truck therefore if something is not working it will help you discover what the situation is and ways to resolve it. You can then evaluate if this can be achieved on your own or in case the job is just too big it is possible to make a reservation for your GTS 125 right into a decent repair garage.
Sym GTS 125 manual