In what circumstances would one need to identify an unknown navaid from a morse signature?
All that the morse ID does is confirm one has the right frequency tuned and the navaid is not officially offline. It does no more and no less. Specifically (despite widespread suggestions to the contrary) it tells you exactly nothing about any failure in your receiving equipment. I've flown with duff VOR and DME equipment which sounded out the correct ident, but wasn't working; the best example was a certain G-xxxx PA28 Archer, used for IMC training
in which the DME would read 5.5 when the distance was 3.7, etc.