Firstly, I'm an amateur. I enjoy recording and editing audio and video but there is much I do not know. Hence my presence here trying to find some assistance from much more qualified individuals.
I recently recorded a live presentation with a lavalier mic and a Zoom H1 recorder in the presenter's jacket pocket. When listening to the audio, all's well until several minutes in when a noise pops up and sticks around for several minutes. It's not room noise, I assume it's from the equipment. There was also a podium in front of the speaker with another mic that could have created interference. I posted it to SoundCloud so folks could hear it firsthand.
I have Audition CS6 at my disposal (though I'm open to using other software if you think that will help) and have attempted noise reduction by capturing a noise print of the sound by itself. That has helped some but it seems to share some frequencies with the speaker's voice and therefore it pops up again when he's speaking.
I wasn't able to access the sound - the site says it isn't there - but it appears that you're doing the right thing. Removing noises, especially intermittent ones, can be tricky. You may want to try a shot at it again - and if you haven't read this, it may help:
I had a case like this a couple of years ago, turned out the sound was coming from an adjoining room. We did not notice it while we were in the room but heard it clearly in the recording. I used the Noise Reduction Process to eleminate most of it. Here is what I did:
1) Captured a noise print from 3.35 to 3.70
2) Select Effects, Noise Reduction/Restoration, Noise Reduction (process)
3) Set Noise Reduction to 63%
4) set Reduce By to 30 db
5) Set Spectral Decay Rate to 65%
6) Set Smoothing to 1
7) Set Precision Factor to 7
8) Set Transistion Width to 0%
9) And most important, adjust the blue line in the graph area. I set the 0 hz point to -30, 2k to -60, 4k to -75, 6k to -80, at 7k I dropped down to -100 and ran a flat line to the end.