choppersrule,

It appears that in your photo the illustration should be labeled 1) too little backlash 2) correct backlash 3) too much backlash. I do agree on the backlash being a possibly culprit of stripping the gear. Too much backlash = small contact patch per tooth = teeth break. I usually adjust it by feel, but one can also slip a piece of notebook paper between the gears and press them together to get the proper backlash. HTH