E22158-SeaTalk-STNG-Converter fault

[kamapavi]

I'm using an e7 MFD, installed 5 years.
When I try to switch from the internal GPS to the external GPS (Raymarine) I get the message:
"The following devices are preventing data source selection:
E22518-SeaTalk-STNG-Converter S/N 1102935
Please see User Manual for details"
I get a similar message when trying to activate other data inputs such as the Autopilot (see attached picture).
I know I could switch GPS sources when e7 first installed, but haven't tried in several years. All the connectors on the converter appear tight.
What should I do next?