Norm, it is indeed necessary to crank the motor in one direction enough to get all the slop out of the drivetrain and then start the calibration. It usually takes me a couple of times to get it spot on, I think the flywheel springs back a fraction and puts another count in at times, at least that's my story. 
I like the foil tape idea, but you have to be careful not to short the smoke heater wires.
