I've got a 32-bit Windows machine that I've been using for several years now with devices on the microphone port for input. I've not used that feature for the last few months though (I mostly do that kind of work in the Winter), and now I find it's not working.
The device is definitely supplying signal at the cord end that goes into the PC microphone jack. The microphone control panel level meter is showing good input signal. If I "Listen" to loopback the microphone to the speakers in the PC, I have a good volume level signal.
However, in my applications (I've tried 4 different ones so far) the signal being input is unusably low. Like barely detectable. I tried increasing the microphone level and gain. That has no impact on what the applications are seeing (but will peg the control panel meter easily and seriously distort the loopback output).
I'm at a loss on how to continue debugging. The sound is definitely coming in to the system. It's on the input side, so I don't have application specific sliders that could have become mis-set like the output side has. Just somehow it's no longer being delivered to applications.