If you need to conduct fixes on your own Tomos 125 SM then it is usually recommended to own a Workshop Manual for reference in the event you need to know the best way to strip off a particular part for example Gearbox and match it again correctly.
Tomos 125 SM Workshop Manuals offers clear special diagnostic guides on your car or truck therefore if something is broken it will help you identify what the problem is and the best way to fix it. After that you can determine if this can be achieved by yourself or if ever the job is simply too big you are able to make a reservation for your 125 SM in to a suitable repair garage.
Tomos 125 SM manual