If you want to do maintenance tasks to your Tomos 125 SM then it is usually a good plan to have access to a Workshop Manual to keep just for reference if you need to know tips on how to take out a specific component for example Brake Discs and match it again in the right way.
Tomos 125 SM Workshop Manuals are able to offer targeted diagnostic facts for your vehicle therefore if something is faulty it can help you ascertain what the issue is and some ways to correct it. You will be able to evaluate if you can do this by yourself or in the event the job is too big you can actually book your 125 SM right into a suitable mechanic.
Tomos 125 SM manual