if you turn clockwise all the way (carefully don't force it!!) it should eventually come to a stop as it 'sits'.
There is an o-ring holding it in place, so if you've unscrewed it (anticlockwise) all the way it may just be sitting outside the thread. Just try going clockwise applying a small amount of pressure and it should engage again, eventually coming to a stop.
I hope you went in all the way and recorded how many turns it took to come to a stop on each after drilling the plugs, so you know what they were set to by the factory?