I've got some of the circuit diags. for the system (courtesy of Raytheon Marine), so I might be able to help. What appears to be the problem, and has the repeater got a display or not? Does the main helm position control work?
Incidentally- a point I have aready checked on, there are no available spares for that system- so it is a complete change throughout the boat or fix the offending assembly.
I may be wrong, but I got the destinct impression from Raytheon that as it's an obsolete system, they do not carry spare assemblies. There may be former service centres, ie before Raytheon took them over, who may well still carry them.
To be on the safe side check with them. I found an Alastair on 02392-693611 x 2023 very helpful - good luck- Stuart
You're not refering to the ST6000+ by any chance?- that's a totally different animal- that IS the latest version. Still contact Raymarine on that number if it is.