So to confirm: You have now tried both a stereo "video" cable, 3.5mm plug (TRRS - 4 contacts on the plug) with red, yellow and white (3 total) RCA connections at the other end AND now a stereo audio cable, 3.5mm plug (TRS - 3 contacts on the plug with a red and white (2 total) RCA connectors at the other end. Is this correct?
If so and you get the crackling with any connection (TV, capture device, etc) made from the camcorder using either cable, it does sound like it is the camcorder, either in the 3.5mm female plug itself or somewhere upstream of that in the output. It seems unlikely that both cables would be bad, and I think that either should have worked as long as the stereo video cable was connected correctly.
I don't think this is problem really systemic to this type of connection on camcorders, but I have had similar problems with stereo audio connections to headphones, etc. (iPod, phone, etc.) So it can be a problem. Yet I have 5 or 6 (miniDV, Hi8 and D8) camcorders all with a similar (though stereo) A/V connection and so far I have never had this problem with them. And I must admit that I've always worried that it is a somewhat fragile connection and could be damaged with a minor mishap or careless use.
Does the plug install securely in the camcorder or is it a bit loose, either side to side or in and out? If you hold it to one side or possibly hold it just less than fully inserted does the sound clear up? Either of these might indicate that one of the contacts in the camcorder is bent or weakened. Here's a jack
with the kind of connections likely to be inside the camcorder jack. The "V" shaped contact should be making the audio connection to the tip (T) of the plug and also securing the plug in the jack.
The fact that turning the plug changes the sound indicates that it could just be that the contacts are dirty. I don't know exactly how I would proceed then but I would try to clean them. If the video is clear and only the audio is cracking then it should be the tip connector that is bad/dirty. Maybe you could dip the plug tip in contact cleaner and put it in and rotate it around pull it in and out, especially the last mm or so, repeating a few times. I would not spray contact cleaner into the female connector...
For reference, the correct cable for your camcorder should be like the one shown in this eBay listing.
To my eyes the 3.5mm TRS connector looks identical to a typical stereo audio cable (and is the standard TRS configuration I assume) so the stereo audio cable should work as a substitute.
I hope you can find a cure... Good luck!