If you have to perform adjustments on your own Aprilia ETX 125 then it will always be a good idea to have a Workshop Manual for a reference should you want to know techniques to take out a certain part for example Wheel Bearing and install it again appropriately.
Aprilia ETX 125 Workshop Manuals gives you targeted diagnostic guidelines with regards to your car or truck so if something is playing up it helps you ascertain what the issue is and tips to resolve it. You can then determine if this can be achieved on your own or if the job is too big you can actually make a reservation for your ETX 125 into a local mechanic.
Aprilia ETX 125 manual