If you are experiencing issues with this type of PTL controller, it is a Legacy item and cannot be supported in terms of repair or electronics servicing, we highly recommend upgrading to the current version of PTL Controller family. 

This changeover will need to be facilitated by an qualified Auto Electrical service provider. 

If the unit is still functioning but you wish to change the Radio link channel, the attached a document outlining how to change the channel of a controller.  Remove the yellow tab from the side of the controller and you will see a dipswitch.

Please note: Only the first 3 switches from the left are operational.

Ensure both the master and the slave controller are set the same setting (channel).