[Cougar429]

The only thing I can think of a faulty extension causing this sort of problem is if there was so much resistance the voltage and/or current present at the servo was far below optimum. You never mentioned it, but was that servo also a lot slower than the other aileron?

One extra point on older systems is that sitting with the battery connected for an extended time can create what is called "Black Wire Disease". This only happens if charge is present in the pack and occurs due to electron transfer in the conductor material and can be equally prevalent in the wire conductor itself or the internals in the switch). Since your switch only interrupts the positive side of the circuit the negative, black side remains connected to the battery. For extended storage the only solution is to disconnect the battery, (that does not prevent it occurring in the battery lead itself). Very old batteries may show voltage, but corrosion can prevent full current flow.

Glad you found the problem, but I would recommend you take a good look at any other extensions since unless you found some physical fault with the one mentioned, (such as a cut wire) they may be borderline, as well.