I purchased a used dx6i that looks almost new for only $85 shipped! It didn't have the datecode sticker anywhere, but I did the test for it. It seems to have a little jump in the throttle stick when it is at idle. It doesn't do it constantly or every time but you can see the monitor move a little without input. It works fine on both my blade cx2 and pz corsair, and all the other sticks seemed to be perfect. Should I send it in anyway?

If it would make you feel better! Part of flying well is having confidence in your equipment set-up and tuning.

So you have another receiver you can check it against?

I am having a wierd glitch on my new Futaba 7c 2.4ghz on the throttle too. Seems to always be in the same spot in flight. ive only had one flight with it so Im gonna check it again. If I take my other plane out and it happens there too...its all going back for replacement.

My 6i didn't have a date code either.  I did the SB as called out by Horizon and found that the pots seemed to be fine.  I called Horizon anyway and was told that I should be good to go but if I would like, send it in and they would check it out. 

If you're unsure, I would send it in to be checked.  No sense in wondering only to suffer an untimely/unfortunate crash and experiencing the "if only" syndrome.

Just my thought.

It never hurts to have a piece of used equipment looked over especially if you don't personally know the previous history. Better safe than sorry. Prepare a short letter to send with it expalining anything you have observed and what you would like them to do.