Just spent some time troubleshooting my parents skype connection with me.
They could hear me, I couldn't hear them. They had this problem intermittently with some people.
After messing around with updating drivers, trying different mics etc, a quick google for logitech e3500 found this link:
http://forums.logitech.com/t5/Video-Chat-Applications-Non/E3500-microphone-not-working/td-p/326579
and the useful message:
I've just had a client with a similar E3500 volume problem. After some experimenting it appears that if the input volume is set above 90-95% the E3500 microphone stop recording. So long as the input volume remains below 90% it works fine.
I can not be sure if this is new behaviour or started following recent updates.
I shall continue looking for other information about this issue.
Setting the mic levels to less than 90 and ALSO changing the skype settings from auto level and setting them lower, and then re-setting to auto and suddenly there's sound. Marvellous.
Lance Paine 01 June 2013