Aileron controls seized

[Tim Wang]

I own a 1967 C337B model and the issue is that the ailerons are seized. It was parked outside over the winter waiting for it's annual to be done. The AME was busy and it sat for months. Now the ailerons don't budge. Tried penetrating oil and removing cable from servo motor without success. The previous owner informed me that there are tubes and bushings in each wing that corrosion can cause the cables to seize. Where is the located and can it be checked? Next step is to remove each cable from the yoke and see if either the left or right side is free and go from there to try and localize the problem.
Any help is appreciated.