Weird tail problem

[Funflyer]

I'm using a 401 gyro with a 9254 servo and it doesn't move smoothly. With power off the servo and tail linkage is smooth, but when the servo is powered up it has a kind of ratchety/ jerky motion. If I put my finger on the servo case I can actually feel it vibrating and you can see the tail blade motion isn't smooth either (this is without the blades spinning). Is this normal???

[helicraze]

Doesn't sound to normal. With it off can you move the arm smoothly? Maybe some gears are stripped. Is it old servo or brandnew?

[Funflyer]

Yes the arm moves smoothly without power. It is a new servo as far as I know, bought it from Ebay. I am running a 6V BEC but have an align stepdown between the gyro and servo so the gyro is 6V and the servo is 5V.

[Funflyer]

I just tested several things; took out the stepdown, double checked that nothing was binding, took apart the servo, etc. And after a lot of checking it doesn't seem as bad as I remember at the field so either a piece of dirt was in the tail bushing or I was making more of it than I should have. At the field I was looking for problems with the tail so it's possible it seemed worse than it is. The absolute only thing I found was the tail slider sticks ever so slightly at full travel next to the tail case (within 2mm). I polished the tail with some fine grit sandpaper to make it smooth and it didn't get quite as much near the tail case. I don't think this affects anything in flight and it is very slight but I'll see if I can smooth it out a little more.

[helicraze]

Make sure there is some lube on the tail slider as they can get sticky

[Funflyer]

I'm using light oil (called "3 in 1" in the U.S.) on the slider. Should I try something a little heavier?

[helicraze]

That should be fine, does the tail slider stick?

[Funflyer]

It just barely sticks when it gets within about 2 mm of the tailcase. The rest of the shaft is smooth. I'm going to polish the tail shaft a little more at the tailcase, but it shouldn't be using that part of the shaft anyway.

[helicraze]

does it fly ok?

[Funflyer]

I've only had a few flights, but I did have one incident of tail oscillation and it isn't holding like I want. I still need to tweak the gain a little more though.