If you want to execute fixes to your Yamaha RD 500 LC then it will always be a good idea to have a Workshop Manual for reference if you want to know proven methods to take out a particular component such as the Brake Discs and match it again safely.
Yamaha RD 500 LC Workshop Manuals offers clear certain diagnostic details on your vehicle therefore if something is broken it can help you identify what the issue is and how you can make it better. You will be able to determine if you can do this by yourself or if the job is just too big you can actually make a booking for your RD 500 LC in with a suitable mechanic.
Yamaha RD 500 LC manual