using a dial indicator to measure backlash
#3
You want the dial indicator to be touching the ring gear at a 90deg angle (perpendicular) this way you get an accurate measurement of the backlash. You will have to eye this out. If the indicator is touching at an angle you will get an incorrect reading die to the angularity. You will have to work at this to get it set properly good luck and i hope you bough a magnetic one.