Good Morning, Although I am not any kind of Expert I am perhaps a long term survivor. So RP80 one practice I have always done for as long I can remember using servos with both new servos and used servos.

Its called by some of us 'burning in the servo' It is simply running the servo continuously back and forth for about ten minutes. In the case of new servos I always do this before installing in the airplane and yes have found some to fail in this way but the rate is quite low maybe 1-2%.

For used servos going into a new airplane: First I carefully move the arm with the servo unplugged from stop to stop looking for gear problems and indeed any slippage doing this is a problem. Next I will plug it into my servo driver listening for any continuous running of the motor, thats bad. At this point I set the servo driver to manual and while holding the servo up to my ear manually go from stop to stop with the servo driver. Doing this you will soon develop an ear for what a heathy servo and gear train sound like. Last I simply Burn in the used servo on the continuous cycle mode with the servo driver as I noted above for new servos.

My orginal servo driver I purchased late sixties or early seventys as an electronics kit was an Ace Servo-cisor and finally gave up two years ago so in the video is my replacement a cheap Hong Kong unit I paid under twenty bucks for and there are many servo drivers out there on the market now.

Anyway here is a short video of it set in the 'cycle' mode to illustrate what I am talking about..

http://www.youtube.com/watch?v=y5hCC...h_0PWTkXPcXnWA

John