Spectrum has a awarning about the reversing y connections. I believe that it counts as a powered reverser and they cause glitching just as you describe intermittently. I even had several do this to me as I converted from 72mhz to 2.4. As a result I have retired all of my reversing y's. Now I use a second channel, reverse the servo, use a brand of servo of another brand with different direction of rotation, or make sure the linkages are set up not to need reversing.
9303's also have a 'notam' about frayed wires on the aileron pot as I remember. That's easy to check by opening the back and checking the pot wires. It's on the JR site as I remember.
John