Generally a check up will cost a total of around $30-$40 by the time you add in shipping etc. This of course depends on what needs to be done to the system, so it does vary. You can find information for sending your system in here as well as a service checklist that you can fill out with the necessary information and send in with your system. Send it in Attn: JR Service.
http://horizon.hobbyshopnow.com/support/