ORIGINAL: JohnBuckner
Just guessing here, ah you said you used a Y on the flaps and I would bet you used a reversing Y as it is often required with flaps on some of these arfs.
Its my bet that this Y is the root of your problem either the connection corrosion Rodney and Gray Beard suggested or something more heinous. I am not an electronics type but I have found a number of cheapie reversing Y's to cause problems.
John
I found the price of them didn't mater. When my instructor had his hobby shop we tested 6 brand new JR Ys and 3 were bad right out of the package. Brand doesn't seem to mater. We didn't test the Futaba Ys but I have seen problems with brand new ones over the years??
From my own use I ran into the slow servo operation using the extensions on big planes. This was before they started gold plating them though and the gold plated extensions do cost quite a bit more. That's when I started soldering in my own extension wires on my servos. Not all radios will allow you to mix so a Y is often needed but as soon as a problem shows up that's the first place I look.