A must watch YouTube video on stylus in the groove!!!
Google Applied Science LP you tube. Should be right at top. Look at those grooves and how the needle is Bouncing!!!! Now explain how important antiskate, null points, etc are. If you thought your stylus was running parallel to the smooth groove walls Well so much for that.
This guy is selling nothing in this video. No hypothesis to let his ego get in the way and no conclusion. Well I thought some of the more technical guys might get a bang out of this, regardless if it might make you rethink your own hypothesis.
Enjoy the ride