Just noticed your question. I use Permatex "Ultra Copper Sensor-Safe RTV" to fix the wires in place. I picked up the current tube at K-Mart, so you shouldn't have any problem finding it. Should you need to substitute another brand, make sure it says that its the "sensor safe" type for automotive use. Like I mentioned earlier - don't use regular clear silicone RTV - that stuff releases acetic acid as it cures, and will munch your servo's electronics in short order.

The procedure is quite simple. Open the bottom of the servo case, goop in enough RTV so that the wires are covered, close the case and wipe away any excess. Set the servo aside for a day or so before using it, as it takes a while for the RTV to cure completely.