I have updated the firmware to the latest and recorded a short file without case and without any filtering - The white noise seems to be similar.

I'm struggling to find the latest firmware - and its ages since I installed it, Is it a .bin file? If so my Mac won't open it.

The test files are without case and its the Green one I purchased recently and used in the field.

I just did a reconfiguration and here's the test files

Here's the original CONFIG file

Thanks Alex I'll try that out - I put it out in the field for three nights in it's new case (I normally use a re-seal bag), and it came back all white noise with some nocturnal bird sound recorded and audible although faint - I then used default setting to test but I will reconfigure and test again.

Thanks Eugenio, I think I'm forming the same conclusion in terms of it's lifespan, although I think it's been out in the field less than a dozen times.