Thanks for the suggestions and comments. However, I have always powered the servos form a separate external power supply with the power supply and the Arduino grounds connect to a common bus. This has no effect on the problem.
Also reading the data via a while loop or as outlined in the code above does not change the problem. Watching the output for the servo signal coming from an Arduino pin shows that a larger time pulse is sent to the servo for positioning.
The data sending programing is displaying the values sent to the serial port, and the glitches randomly occur at different points in the sequence. I suspect some type of timing issue but cannot seem to run it down.
Thanks again 