My sincere thanks to you (cbrillow) for you advice / clarification. I suspected that the wiring would not be stereo (for a guitar application), but I have no idea why a Sleve, ring, tip configuration ¼" plug would be used. I do not wish to damage any electronics by making a wrong connection.
I recently inherited responsibility for the G10 Relay at my church, but (unfortunately) without the user manual. My guitar must be one of the incompatible cases (other instruments work correctly).
I could not find a thread on the forum of a FAQ solution. I will endeavour to find a user manual.
regards Colin