If you wish to do maintenance on your Derbi Terra 125 then it is always a great idea to possess a Workshop Manual to use as a guide if you want to know tips on how to take off a certain component such as the Clutch and install it again in the right way.
Derbi Terra 125 Workshop Manuals gives you identifiable diagnostic info for the automobile therefore if something is faulty it will help you find out what the situation is and the way to repair it. After that you can assess if this can be done on your own or that the job is simply too big you can make a booking for your Terra 125 into a decent friendly mechanic.
Derbi Terra 125 manual