hey Casey,
if the nocks are too tight, they will wreak havoc with the fine tuning, best tension is as follows- clip the arrow onto the string, hold the bow so the arrow is pointing down, then tap the string kinda close to the arrow about as hard as you might tap the enter key on the keyboard- so a little firm rap- but dont clout it
the arrow should fall off the string. too tight it will create problems- too loose and can be a bit dangerous- possibly lead to a dryfire- if they slipped off the string unbeknownst to you.
to adjust the nocks "grip" dip just the horns of the nock into just boiled water, for a few seconds, then either squeeze them together slightly - or pull them apart slightly, then while holding them-dip the nock and your fingers under the cold water running tap- well thats what i do- boil a coffee mug of water and take it over to the sink- turn the cold water tap onto a light run.
dont over heat the nocks- to the point where they are too pliable , and dont heat the glue portion of the nock.- if the nocks have worn a bunch over time- they can be retightened - to be like new
hitting the shelf- i would look at nocking position on the string- like you did. just check that your shelf has a nice radius from belly to back- it should not be flat- where the arrow contacts the shelf should be the highest point.
good luck
cheers!