If you want to carry out repairs on your own Derbi Senda 125 then it is always a good plan to have access to a Workshop Manual to use as reference in the event you want to know the way to take out a specific part for example the Door and match it again efficiently.
Derbi Senda 125 Workshop Manuals will provide you with precise diagnostic guides on your vehicle therefore if something is broken it will help you understand what the problem is and how you can fix it. After that you can determine if you can do this by yourself or in case the job is just too big you could make a booking for your Senda 125 into a trusted mechanic.
Derbi Senda 125 manual