My final update (I think)
My Sirius signal started going all over the place and the nav signal had dropped. I removed the head unit and found that the am/fm radio antenna cable had pushed the nav and Sirius antennas off their pads when I installed the head unit. Rerouted the regular antenna and stuck the other two to their pads with a small gob of silicone sealer. All is good once again.
Larry