Default Low/no mic issue: Fixed

My old Sensation - passed down to a relative - had an earlier Viper rom. After they accidentally smashed the touch screen, we got it repaired and, somewhere between that and upgrading firmware/rom, the mic issue appeared i.e. the in-caller could not hear what was said at our end.
After sending it off to get a new mic it still didn't work!
Video recording was fine but Voice Recorder or In-Call, NO.
In desperation I spent the best part of 3 hours reverting firmware and roms until finally I got the mic working again with good old CoreDroid 6.0 albeit a bit low/under water. Then I put the latest firmware on and hey presto it's working again. Still not for voice recorder but we can live with that.
(Makes me wonder how many microphones are there!).

Just goes to show that some issues may not be just hardware failures!