If you choose to do repairs for your Triumph TSS then it is usually recommended to have access to a Workshop Manual for reference if perhaps you need to know proven methods to take out a particular part like the Gearbox and match it again adequately.
Triumph TSS Workshop Manuals will give you certain diagnostic facts with regards to your car or truck so if something is wrong it will help you identify what the issue is and methods to correct it. After that you can determine if this can be done by yourself or that the job is too big you can actually book your TSS into a suitable car garage.
Triumph TSS manual