I'm interested in people describing how a pea whistle actually malfunctioned on them, what brand it was, the conditions, etc. As far as trying a pea whistle WITHOUT the pea, all my pea whistles must be destroyed in order to remove the pea. So, no, I did not try this!
I never had a pea whistle malfuntion. I did take the cork pea out of a couple of cheepies just to see what would happed. They lost their characteristic trill and sounded like a medium pitched bosun's whistle, but still worked. I suppose if the resonance chamber or labium (air splitter) gets ice built up, it would alter the airflow enough to prevent getting any good volume.
Also, the current crop of Storm whistles do have a pea. It's not the split ring that you're hearing rattling.