you can mark the hole in the center of the jack. you can use a small nail also to do this. this mark is very important because it is where you will drill a 1/4" hole. so keep the mark in the very center of the hack hole. if you are off to the side just a little bit the jack will not fit correctly in this small area.
when i tried to fit the jack in, it did not work at first because the small ring that screws onto the jack did not lay flat because some plastic was in the way. so i used my soldering iron to melt 