If you want to carry out maintenance tasks on your Derbi Senda Supermotard then it is usually a great idea to have a Workshop Manual to keep just for reference in the event that you want to know techniques to take off a particular component including Gearbox and fit it again adequately.
Derbi Senda Supermotard Workshop Manuals can provide targeted diagnostic information on your car so if something is not working it can help you figure out what the issue is and easy methods to fix it. You will be able to assess if this can be achieved by yourself or if the job is just too big you are able to book your Senda Supermotard in with a decent repair garage.
Derbi Senda Supermotard manual