I am happy to report that I have managed to "wear out" a pen arm servo.
Tried the excellent "Stipple" program yesterday and "fine tuned" the eggbot parameters to manage about four points per second as stated possible in another post on the forum. Midway through the plot of 9400 points the servo went "belly up" and failed to move. Plugging my spare servo (with the plot still going - pen down all the time) verified that the servo was bad, the spare moved like it was supposed to.
"Dissecting" the failed servo I found the motor to be bad - helping it start by turning it by hand would have it moving for a while.
My servo might work a little "harder" than usual as I have a rubber band to provide some "extra" down-force on my pen arm for my ball point pens to work reliably.
Anyone else plotted enough eggs to wear out a servo?