The Icom web page doesn't list FM stereo in the specs.
The owners manuyl does list FM stero in the specs and the
diagram doesn't show a MPX decoder/
And my PRC1000 only has one audio line, as determined
by moving a single shunt to change from spkear ot line for the
AF output.

You might want to check yours again, I suspect you will find
that it, like all the other PCR1000s dosen't have FM stero.
A simple test is to use a stero headset. I bet you only have
audio in the left side.

Sorry I can't spell all that well under good circumstances, but
today I am down with the flu and the cough syryp is a little too
strong.

Terry