If you choose to undertake maintenance on your own Yamaha XTZ 250 Lander then it is usually recommended to have access to a Workshop Manual to use as a guide in case that you need to know the best ways to remove a specific component much like the Gearbox and match it again in the correct manner.
Yamaha XTZ 250 Lander Workshop Manuals provides precise diagnostic information for your vehicle so if something is not working it can help you ascertain what the issue is and the best way to resolve it. After that you can decide if you can do this by yourself or that the job is just too big you can actually make a booking for your XTZ 250 Lander in to a decent garage.
Yamaha XTZ 250 Lander manual