Any idea how to remove the clicks and low frequency "helicopter" noise? I've had limited success, but I'm not able to get rid of them completely. I am trying to restore 25-year-old VHS tapes.
That is some pretty ugly motor-boating.
Attached is as screen shot of the waveform of the intruding signal. About 10 Hz in the primary peaks, and 30 Hz on the secondary peaks.
Have you tried playing it in several different players direct to a TV set? Do all have the motor-boating about equally?
Also attached is as quick filter of the sound using Audition restoration. While it does not sound good, at least the voice can be understood above the noise. (No attempt was made to optimize the filtration.)
That's outright FM interference, and you won't be able to remove it. Even reducing it is unlikely, as it dominates the audio channels. The recording device was too close to a phone, radar detector, etc.
Trying to remove this will result in the very distorted audio as posted by dpalomaki.