Do yourself a favour and ditch the single servo on the PT-40. I did a mod on mine, and but in two aileron servos, it is much easier to get them set up correctly and I had a problem with the servo control rods in the original config, they have a tendency to be blocked if the wing is not on perfectly. There is also a bit more redundency with two servos, if you lose one for some reason you should have enough control to get back down, it would not be great, but it would work.

Some will tell you that two servos is overkill in that plane, but it has worked out well for me. I have had two, one build with a single servo, the other with two, and I can tell you the second is a much better airplane. BTW - the mod will take about 30 minutes, really easy to do.

Good luck!