Rattle behind the gauges (Annoying!!! argghh!!!)

I have a rattle behind the gauges that is sooOO,,, annoyINGGG!! aaaarrgrghhhh!! I have pulled the cluster out, and tie wrapped and foam insulated everything!!! there seems to be no possible way that anything could rattle back there!!
Just when you think you finally stopped it, there it is..,, tap, tap ,,rattle rattle!! arrgghhgh!! think...,,, it is..,,, THE DEVIL!!!!! he is back there!! tapping away!! just trying to piss me OFFF!!!

But no..,, seriously, does anyone else have this happening???? It sounds like the speedo cable vibrating against something metallic, but I insulated the bejeebers out of it, and I used a generous amount of wheel bearing grease on the inner cable..,, and it is still there!! Any one who has had this same rattle noise, if you can PLEASE tell me how you corrected it, I would be very thankful to you!! (And no, don't tell me to sell it and buy something else.., PLEASE!!! )

It could be the cable itself. I havent had it with a mazda but have had it with another truck.. the cable was shot and needed replacement.

Does it come and go with the ambient temperature?
I believe you can actually buy a lube just for speedo cables!
Or if it was me... just grab some white grease

OK ,well it was a combination of ...,, the cable finally broke, and that's the end of some of the noise, but the incessant tapping noise was the engine to firewall ground strap. I had bolted two cables together to add some length to it, and the bolt betwixt them was tapping against the firewall. I could not see this, as it had fallen down behind the cylinder head.
But I found a universal speedo cable repair kit at Advance auto for 11 dollars, I think is what I paid. I will install it when the rain quits in a couple a days.