am using the towerpro MG995. I tried to center it 5 minutes ago, and got one to silent. The slightes bump started it off again. Found this post at www.rcuniverse.com
I wrote a review of these a while back.
* all metal gears -- pertty tough
* cheap (and I mean "cheap"
* seem to have good torque and are moderately fast
* very poor match between electronics and mechanics produces bad overshoot
* feedback pots simply don't last -- resulting in lots of jittering around neutral
* gear-mesh, centering and stability highly variable from one unit to another
In summary, if you get a good one they're okay and will work (for a while). Chances are you won't get a good one though and you'll notice that they rock back and forth around neutral, overshoot past the commanded position and generally have poor resolution.
I bought 14 of these servos and here are the stats so far:
1 was pretty good and is still in service after about 6 months, although the feedback pot is now so worn that I'll be removing it because it shakes like it has the DTs.
1 failed within 5 minutes of installation -- and almost brought a plane down with it -- the output arm just gyrated wildly for about 30 seconds -- then it came right. Hasn't faulted again but I'm not about to risk it.
4 have not been accurate or stable enough to merit using on any aircraft I value
2 were stripped and I used the servo amps to replace those in a pair of Hitec HS425BB standard servos. This makes a *very* nice little digital servo that is fast, accurate and has great holding power. The difference between these modified HS425s and the original MG995s from which the amps were pilfered shows just how bad the MG995's pot and geartrain really are.
The rest are sitting under my bench. Maybe I'll build an RC doorstop one day and they'll be just perfect for that :-)
Bottom-line: They're okay but they're really cheap and risky.
So I might just have an edsel........
mabye friction is a problem, close to "zero", while there is still the noise, it will sometimes increment in ~1/2 second intervals. I did not intentionally remove the grease, but did have to dremel away the stop pins, probably lost a bit (or lots) of grease, as I haad to totally disassemble the gear assembly. Ok, I'm off to find some servo lube.........