ORIGINAL: Rcpilet
XJet, I disagree with you about the pots. They DO have an effect on the centering of a servo. The pots in the lower end Hitec servosd are known to be poor quality. I guess thats why Hitec replaced the pots in the 645 servos I had. They wouldn't center and I sent them to Hitec for service. They all came back with new pots. Perhaps Hitec doesn't know how to service their own equipment?
Poor pots *can* wear more quickly than higher quality ones and that can cause centering/accuracy issues after a while -- but a poor quality pot does not mean bad centering out of the box. Believe it or not but you'd not notice the difference between a $50c pot and a $5 pot until the former started to wear.
If you have a servo that was working well but starts to jitter around center then there's a good chance that the pot is worn but if it centers poorly from new then the fault lies elsewhere.
You guys are all slamming JR about gear problems. I've been running the same 8411 servos in a 50cc airframe for 4yrs and I haven't needed to replace the gears. They are as tight as the day I installed them--some 450 flights ago.
I think most of the people reporting worn gears are flying gasers with large (aka "heavy" control surfaces. This setup can hammer a gearset and case much faster wear than when the same servo is used (say) on a warbird with much smaller and ligher surfaces that also have far less mechanical advantage against the servo.
However, it's been my observation that (for some reason) JR's gears still wear out quicker than Hitec or Futaba when used in exactly the same kind of setup and airframe.
But, thats not the servo I recommended to him anyway. I recommended the 4721 coreless. Those are nylon gears and they don't wear out in a season.
I'm sorry but your "x-spurtise" is showing again :-) Nylon geared servos are *not* suitable for gas-powered planes (especially an aerobatic ship like a Yak). The stresses put upon them by a vibrating gas engine and those large control surfaces is just asking for trouble.
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XJet