We see corroded USB ports regularly because users continue to close the USB cap with a screwdriver all the way down. That might get the O-Ring damaged in the threads. Result is a leak and (worst case) end-of-life of the entire unit (The USB port is NOT replaceable in the 2C or 2N!).
The USB cap is designed to be closed with the USB connector as the tool!
Only close it until it's flush with the mating alloy part.
So, if your Cap looks like this:
Your USB port will look like this soon:
And the OSTC will be, unfortunately, end-of-life.
Regards,
Matthias