Sirius (via TOYSC1) ”No Tuner" error

I've had an aftermarket Sirius receiver integrated into my 2008 Prius since shortly after buying it new back in 2008. The tuner module sits in the center console in a Directed Electronics SCVDOC1 dock and integrates with the touchscreen audio controls via a Directed Electronics TOYSC1 adapter that I've tucked into a corner of the dash. It's a nice installation and the wires aren't visible.

About a year ago when the weather started warming up I began occasionally getting an error condition where the touchscreen would display "No Tuner" at the top of the audio screen (where the tuned channel info normally appears) and when this happened I get no audio from the Sirius tuner. Eventually I discovered that I could reset the error by pulling the tuner out of the dock and reinserting it, but this isn't a reliable way to correct the the problem and sometimes it recurs within a couple of minutes.

I first suspected the tuner module so I bought another of the same model Sirius tuner that I had, but after paying the $15 fee to transfer the Sirius account to the replacement tuner I kept getting the No Tuner error.

The Directed Electronics components are long obsolete so I haven't had any luck in finding replacements, but a couple of weeks ago I found a TOYSC1 on eBay in new condition. But shortly after installing the replacement module I'm still getting the No Tuner errors.

I still have the basic Dock & Play dock from Sirius so I could try plugging the tuner directly into the Aux jack but I don't see that as a viable long-term solution since I'd lose touchscreen selection of channels (and frankly, with an unlimited LTE plan on my cellphone, streaming audio sounds better than most satellite radio channels anyway).

I'm wondering if anyone else has run into No Tuner situation with a setup like mine, and whether they've been able to fix it. Thanks for any insight.