I had pretty much the same problem with a 127DF on a DP Edge 540T with 5945's on the elevators and 8611 on the rudder. I had a 6 volt battery. When the rudder was deflected 1/2 and I held it there, it would just bump once or twice and stop. It didn't do it at neutral, only under load. Then I plugged a 5945 elevator servo into the rudder channel and same exact thing on that elevator half. Then I started to see the elevator channel doing the same thing. It turns out that it seemed to get worse near the 3rd and 4th channel of the rx. I tried different tx's and the same exact thing happened. I replaced the rx with a brand new 148DF and the problem is completely gone. I am using the same battery and extensions as before. I'm glad I found this in my basement.

I have the same model rx in a CAP232 25% with (5) 5645's and there is no glitches at all. Not sure if it's just some rx's or maybe I damaged this one, not sure. The one I'm having problems with was in a crash (not a bad one though, more like a hard landing). I used it in a Funtana 40 for many flights with no problems so I think it's the high current digitals that it does not like.

Joe