Please reference the following link and video for an excellent description on cleaning the contact area of a potentiometer to restore proper operation of it:
My Dx6i was manufactured in Mar 2012. It has been used for less than 200 flights; the elevator gimbal presented glitch problems similar to that described in above link.
I completed the steps below to eliminate the elevator glitch: virtually no control movement as seen on the monitor.
1) Remove rear of transmitter - 6 screws
2) Position the rear of the Tx on flat surface, and gently move the front of half of the Tx to a vertical position and "lock" it into the rear half at the bottom. It will sit there quite nicely, but I added some tape for extra protection just in case. Please see pictures.
3) Unplug the the elevator connector
4) Remove the gimbal's 4 allen screws on the front side of the Tx.
5) Cut the tie wrap associated with the wire bundle that the elevator wires are a part of.
6) Remove the rear cover of the potentiometer (elevator in my case) by carefully sliding a razor blade under each of the 3 tabs and bend them to make an angle slightly less than 90 from the pot rear plate. They do not have to be lifted to a full 90 deg before the rear plate of the pot can be removed.
7) Dip a Q-tip in alcohol or other suitable solvent and carefully wipe the contact area of the pot plate.
Wipe the pot wipers with alcohol as well - I did not do this.
9) If you have a device that will puff air (like a slide cleaner bulb), blow air on both the wipers and rear contact plate - maybe over kill.
10) Reassemble in reverse. Reinstall a tie wrap.
Additional Info: All the steps can be completed comfortably in about an hour. I measured the pot to be 5.1 to 5.2kΩ. One could say the Spektrum Tx (ie, potentiometers) is not robust if a pot causes trouble near 200 flight uses. Others seem to complain of this problem beyond the recall period. My Tx was manufactured after Spectrum supposedly corrected a problem with potentiometers. It will take a year or two to validate that the problem I corrected does not reoccur.