RE: 12z/14mz HD gimble springs
I have tried three different sets of springs on my 12FGA. The ones from Futaba, Tower, and Radio South. I did not measure them but to me, the Futaba springs for the 12 and 14 series are slightly smaller in diameter than the heavy duty set from Tower. This is also evident when they are installed - the heavy duty springs from Tower make contact with the surrounding walls. I suspect that over time they will damage he radio. They are however, stiffer than the Futaba springs for the 12/14 series and the springs from Radio South. The set from Radio South are smaller in diameter and those are the ones I decided to use. Good luck.
Princeton